Merge git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus
* git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus:
lguest: Fix in/out emulation
lguest: Fix translation count about wikipedia's cpuid page
lguest: Fix three simple typos in comments
lguest: update comments
lguest: Simplify device initialization.
lguest: don't rewrite vmcall instructions
lguest: remove remaining vmcall
lguest: use a special 1:1 linear pagetable mode until first switch.
lguest: Do not exit on non-fatal errors
diff --git a/Documentation/virtual/lguest/lguest.c b/Documentation/virtual/lguest/lguest.c
index cd9d6af..043bd7d 100644
--- a/Documentation/virtual/lguest/lguest.c
+++ b/Documentation/virtual/lguest/lguest.c
@@ -51,7 +51,7 @@
#include <asm/bootparam.h>
#include "../../../include/linux/lguest_launcher.h"
/*L:110
- * We can ignore the 42 include files we need for this program, but I do want
+ * We can ignore the 43 include files we need for this program, but I do want
* to draw attention to the use of kernel-style types.
*
* As Linus said, "C is a Spartan language, and so should your naming be." I
@@ -65,7 +65,6 @@
typedef uint8_t u8;
/*:*/
-#define PAGE_PRESENT 0x7 /* Present, RW, Execute */
#define BRIDGE_PFX "bridge:"
#ifndef SIOCBRADDIF
#define SIOCBRADDIF 0x89a2 /* add interface to bridge */
@@ -861,8 +860,10 @@
/* writev can return a partial write, so we loop here. */
while (!iov_empty(iov, out)) {
int len = writev(STDOUT_FILENO, iov, out);
- if (len <= 0)
- err(1, "Write to stdout gave %i", len);
+ if (len <= 0) {
+ warn("Write to stdout gave %i (%d)", len, errno);
+ break;
+ }
iov_consume(iov, out, len);
}
@@ -898,7 +899,7 @@
* same format: what a coincidence!
*/
if (writev(net_info->tunfd, iov, out) < 0)
- errx(1, "Write to tun failed?");
+ warnx("Write to tun failed (%d)?", errno);
/*
* Done with that one; wait_for_vq_desc() will send the interrupt if
@@ -955,7 +956,7 @@
*/
len = readv(net_info->tunfd, iov, in);
if (len <= 0)
- err(1, "Failed to read from tun.");
+ warn("Failed to read from tun (%d).", errno);
/*
* Mark that packet buffer as used, but don't interrupt here. We want
@@ -1093,9 +1094,10 @@
warnx("Device %s configuration FAILED", dev->name);
if (dev->running)
reset_device(dev);
- } else if (dev->desc->status & VIRTIO_CONFIG_S_DRIVER_OK) {
- if (!dev->running)
- start_device(dev);
+ } else {
+ if (dev->running)
+ err(1, "Device %s features finalized twice", dev->name);
+ start_device(dev);
}
}
@@ -1120,25 +1122,11 @@
return;
}
- /*
- * Devices *can* be used before status is set to DRIVER_OK.
- * The original plan was that they would never do this: they
- * would always finish setting up their status bits before
- * actually touching the virtqueues. In practice, we allowed
- * them to, and they do (eg. the disk probes for partition
- * tables as part of initialization).
- *
- * If we see this, we start the device: once it's running, we
- * expect the device to catch all the notifications.
- */
+ /* Devices should not be used before features are finalized. */
for (vq = i->vq; vq; vq = vq->next) {
if (addr != vq->config.pfn*getpagesize())
continue;
- if (i->running)
- errx(1, "Notification on running %s", i->name);
- /* This just calls create_thread() for each virtqueue */
- start_device(i);
- return;
+ errx(1, "Notification on %s before setup!", i->name);
}
}
@@ -1370,7 +1358,7 @@
* --sharenet=<name> option which opens or creates a named pipe. This can be
* used to send packets to another guest in a 1:1 manner.
*
- * More sopisticated is to use one of the tools developed for project like UML
+ * More sophisticated is to use one of the tools developed for project like UML
* to do networking.
*
* Faster is to do virtio bonding in kernel. Doing this 1:1 would be
@@ -1380,7 +1368,7 @@
* multiple inter-guest channels behind one interface, although it would
* require some manner of hotplugging new virtio channels.
*
- * Finally, we could implement a virtio network switch in the kernel.
+ * Finally, we could use a virtio network switch in the kernel, ie. vhost.
:*/
static u32 str2ip(const char *ipaddr)
@@ -2017,10 +2005,7 @@
/* Tell the entry path not to try to reload segment registers. */
boot->hdr.loadflags |= KEEP_SEGMENTS;
- /*
- * We tell the kernel to initialize the Guest: this returns the open
- * /dev/lguest file descriptor.
- */
+ /* We tell the kernel to initialize the Guest. */
tell_kernel(start);
/* Ensure that we terminate if a device-servicing child dies. */
diff --git a/arch/x86/include/asm/lguest_hcall.h b/arch/x86/include/asm/lguest_hcall.h
index b60f292..879fd7d 100644
--- a/arch/x86/include/asm/lguest_hcall.h
+++ b/arch/x86/include/asm/lguest_hcall.h
@@ -61,6 +61,7 @@
: "memory");
return call;
}
+/*:*/
/* Can't use our min() macro here: needs to be a constant */
#define LGUEST_IRQS (NR_IRQS < 32 ? NR_IRQS: 32)
diff --git a/arch/x86/kernel/asm-offsets_32.c b/arch/x86/kernel/asm-offsets_32.c
index c29d631..395a10e 100644
--- a/arch/x86/kernel/asm-offsets_32.c
+++ b/arch/x86/kernel/asm-offsets_32.c
@@ -63,7 +63,6 @@
BLANK();
OFFSET(LGUEST_DATA_irq_enabled, lguest_data, irq_enabled);
OFFSET(LGUEST_DATA_irq_pending, lguest_data, irq_pending);
- OFFSET(LGUEST_DATA_pgdir, lguest_data, pgdir);
BLANK();
OFFSET(LGUEST_PAGES_host_gdt_desc, lguest_pages, state.host_gdt_desc);
diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index db832fd..13ee258 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -71,7 +71,8 @@
#include <asm/stackprotector.h>
#include <asm/reboot.h> /* for struct machine_ops */
-/*G:010 Welcome to the Guest!
+/*G:010
+ * Welcome to the Guest!
*
* The Guest in our tale is a simple creature: identical to the Host but
* behaving in simplified but equivalent ways. In particular, the Guest is the
@@ -190,15 +191,23 @@
#endif
/*G:036
- * When lazy mode is turned off reset the per-cpu lazy mode variable and then
- * issue the do-nothing hypercall to flush any stored calls.
-:*/
+ * When lazy mode is turned off, we issue the do-nothing hypercall to
+ * flush any stored calls, and call the generic helper to reset the
+ * per-cpu lazy mode variable.
+ */
static void lguest_leave_lazy_mmu_mode(void)
{
hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0, 0);
paravirt_leave_lazy_mmu();
}
+/*
+ * We also catch the end of context switch; we enter lazy mode for much of
+ * that too, so again we need to flush here.
+ *
+ * (Technically, this is lazy CPU mode, and normally we're in lazy MMU
+ * mode, but unlike Xen, lguest doesn't care about the difference).
+ */
static void lguest_end_context_switch(struct task_struct *next)
{
hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0, 0);
@@ -391,7 +400,7 @@
* giant ball of hair. Its entry in the current Intel manual runs to 28 pages.
*
* This instruction even it has its own Wikipedia entry. The Wikipedia entry
- * has been translated into 5 languages. I am not making this up!
+ * has been translated into 6 languages. I am not making this up!
*
* We could get funky here and identify ourselves as "GenuineLguest", but
* instead we just use the real "cpuid" instruction. Then I pretty much turned
@@ -458,7 +467,7 @@
/*
* PAE systems can mark pages as non-executable. Linux calls this the
* NX bit. Intel calls it XD (eXecute Disable), AMD EVP (Enhanced
- * Virus Protection). We just switch turn if off here, since we don't
+ * Virus Protection). We just switch it off here, since we don't
* support it.
*/
case 0x80000001:
@@ -520,17 +529,16 @@
/* See lguest_set_pte() below. */
static bool cr3_changed = false;
+static unsigned long current_cr3;
/*
* cr3 is the current toplevel pagetable page: the principle is the same as
- * cr0. Keep a local copy, and tell the Host when it changes. The only
- * difference is that our local copy is in lguest_data because the Host needs
- * to set it upon our initial hypercall.
+ * cr0. Keep a local copy, and tell the Host when it changes.
*/
static void lguest_write_cr3(unsigned long cr3)
{
- lguest_data.pgdir = cr3;
lazy_hcall1(LHCALL_NEW_PGTABLE, cr3);
+ current_cr3 = cr3;
/* These two page tables are simple, linear, and used during boot */
if (cr3 != __pa(swapper_pg_dir) && cr3 != __pa(initial_page_table))
@@ -539,7 +547,7 @@
static unsigned long lguest_read_cr3(void)
{
- return lguest_data.pgdir;
+ return current_cr3;
}
/* cr4 is used to enable and disable PGE, but we don't care. */
@@ -641,7 +649,7 @@
/*
* The Guest calls this after it has set a second-level entry (pte), ie. to map
- * a page into a process' address space. Wetell the Host the toplevel and
+ * a page into a process' address space. We tell the Host the toplevel and
* address this corresponds to. The Guest uses one pagetable per process, so
* we need to tell the Host which one we're changing (mm->pgd).
*/
@@ -758,7 +766,7 @@
static void lguest_flush_tlb_single(unsigned long addr)
{
/* Simply set it to zero: if it was not, it will fault back in. */
- lazy_hcall3(LHCALL_SET_PTE, lguest_data.pgdir, addr, 0);
+ lazy_hcall3(LHCALL_SET_PTE, current_cr3, addr, 0);
}
/*
@@ -1140,7 +1148,7 @@
static __init char *lguest_memory_setup(void)
{
/*
- *The Linux bootloader header contains an "e820" memory map: the
+ * The Linux bootloader header contains an "e820" memory map: the
* Launcher populated the first entry with our memory limit.
*/
e820_add_region(boot_params.e820_map[0].addr,
diff --git a/arch/x86/lguest/i386_head.S b/arch/x86/lguest/i386_head.S
index 4f420c2f..6ddfe4f 100644
--- a/arch/x86/lguest/i386_head.S
+++ b/arch/x86/lguest/i386_head.S
@@ -6,18 +6,22 @@
#include <asm/processor-flags.h>
/*G:020
- * Our story starts with the kernel booting into startup_32 in
- * arch/x86/kernel/head_32.S. It expects a boot header, which is created by
- * the bootloader (the Launcher in our case).
+
+ * Our story starts with the bzImage: booting starts at startup_32 in
+ * arch/x86/boot/compressed/head_32.S. This merely uncompresses the real
+ * kernel in place and then jumps into it: startup_32 in
+ * arch/x86/kernel/head_32.S. Both routines expects a boot header in the %esi
+ * register, which is created by the bootloader (the Launcher in our case).
*
* The startup_32 function does very little: it clears the uninitialized global
* C variables which we expect to be zero (ie. BSS) and then copies the boot
- * header and kernel command line somewhere safe. Finally it checks the
- * 'hardware_subarch' field. This was introduced in 2.6.24 for lguest and Xen:
- * if it's set to '1' (lguest's assigned number), then it calls us here.
+ * header and kernel command line somewhere safe, and populates some initial
+ * page tables. Finally it checks the 'hardware_subarch' field. This was
+ * introduced in 2.6.24 for lguest and Xen: if it's set to '1' (lguest's
+ * assigned number), then it calls us here.
*
* WARNING: be very careful here! We're running at addresses equal to physical
- * addesses (around 0), not above PAGE_OFFSET as most code expectes
+ * addresses (around 0), not above PAGE_OFFSET as most code expects
* (eg. 0xC0000000). Jumps are relative, so they're OK, but we can't touch any
* data without remembering to subtract __PAGE_OFFSET!
*
@@ -27,13 +31,18 @@
.section .init.text, "ax", @progbits
ENTRY(lguest_entry)
/*
- * We make the "initialization" hypercall now to tell the Host about
- * us, and also find out where it put our page tables.
+ * We make the "initialization" hypercall now to tell the Host where
+ * our lguest_data struct is.
*/
movl $LHCALL_LGUEST_INIT, %eax
movl $lguest_data - __PAGE_OFFSET, %ebx
int $LGUEST_TRAP_ENTRY
+ /* Now turn our pagetables on; setup by arch/x86/kernel/head_32.S. */
+ movl $LHCALL_NEW_PGTABLE, %eax
+ movl $(initial_page_table - __PAGE_OFFSET), %ebx
+ int $LGUEST_TRAP_ENTRY
+
/* Set up the initial stack so we can run C code. */
movl $(init_thread_union+THREAD_SIZE),%esp
@@ -96,12 +105,8 @@
*/
pushl %eax
movl $LHCALL_SEND_INTERRUPTS, %eax
- /*
- * This is a vmcall instruction (same thing that KVM uses). Older
- * assembler versions might not know the "vmcall" instruction, so we
- * create one manually here.
- */
- .byte 0x0f,0x01,0xc1 /* KVM_HYPERCALL */
+ /* This is the actual hypercall trap. */
+ int $LGUEST_TRAP_ENTRY
/* Put eax back the way we found it. */
popl %eax
ret
diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c
index efa2024..2535933 100644
--- a/drivers/lguest/core.c
+++ b/drivers/lguest/core.c
@@ -117,7 +117,7 @@
/*
* Now the Switcher is mapped at the right address, we can't fail!
- * Copy in the compiled-in Switcher code (from <arch>_switcher.S).
+ * Copy in the compiled-in Switcher code (from x86/switcher_32.S).
*/
memcpy(switcher_vma->addr, start_switcher_text,
end_switcher_text - start_switcher_text);
diff --git a/drivers/lguest/interrupts_and_traps.c b/drivers/lguest/interrupts_and_traps.c
index daaf866..28433a1 100644
--- a/drivers/lguest/interrupts_and_traps.c
+++ b/drivers/lguest/interrupts_and_traps.c
@@ -375,11 +375,9 @@
/*
* The Host needs to see page faults (for shadow paging and to save the
* fault address), general protection faults (in/out emulation) and
- * device not available (TS handling), invalid opcode fault (kvm hcall),
- * and of course, the hypercall trap.
+ * device not available (TS handling) and of course, the hypercall trap.
*/
- return num != 14 && num != 13 && num != 7 &&
- num != 6 && num != LGUEST_TRAP_ENTRY;
+ return num != 14 && num != 13 && num != 7 && num != LGUEST_TRAP_ENTRY;
}
/*:*/
@@ -429,8 +427,8 @@
/*
* Direct traps also mean that we need to know whenever the Guest wants to use
- * a different kernel stack, so we can change the IDT entries to use that
- * stack. The IDT entries expect a virtual address, so unlike most addresses
+ * a different kernel stack, so we can change the guest TSS to use that
+ * stack. The TSS entries expect a virtual address, so unlike most addresses
* the Guest gives us, the "esp" (stack pointer) value here is virtual, not
* physical.
*
diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h
index 9136411..295df06 100644
--- a/drivers/lguest/lg.h
+++ b/drivers/lguest/lg.h
@@ -59,6 +59,8 @@
struct lguest_pages *last_pages;
+ /* Initialization mode: linear map everything. */
+ bool linear_pages;
int cpu_pgd; /* Which pgd this cpu is currently using */
/* If a hypercall was asked for, this points to the arguments. */
diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c
index 69c84a1..5289ffa 100644
--- a/drivers/lguest/lguest_device.c
+++ b/drivers/lguest/lguest_device.c
@@ -109,6 +109,17 @@
}
/*
+ * To notify on reset or feature finalization, we (ab)use the NOTIFY
+ * hypercall, with the descriptor address of the device.
+ */
+static void status_notify(struct virtio_device *vdev)
+{
+ unsigned long offset = (void *)to_lgdev(vdev)->desc - lguest_devices;
+
+ hcall(LHCALL_NOTIFY, (max_pfn << PAGE_SHIFT) + offset, 0, 0, 0);
+}
+
+/*
* The virtio core takes the features the Host offers, and copies the ones
* supported by the driver into the vdev->features array. Once that's all
* sorted out, this routine is called so we can tell the Host which features we
@@ -135,6 +146,9 @@
if (test_bit(i, vdev->features))
out_features[i / 8] |= (1 << (i % 8));
}
+
+ /* Tell Host we've finished with this device's feature negotiation */
+ status_notify(vdev);
}
/* Once they've found a field, getting a copy of it is easy. */
@@ -168,28 +182,21 @@
return to_lgdev(vdev)->desc->status;
}
-/*
- * To notify on status updates, we (ab)use the NOTIFY hypercall, with the
- * descriptor address of the device. A zero status means "reset".
- */
-static void set_status(struct virtio_device *vdev, u8 status)
-{
- unsigned long offset = (void *)to_lgdev(vdev)->desc - lguest_devices;
-
- /* We set the status. */
- to_lgdev(vdev)->desc->status = status;
- hcall(LHCALL_NOTIFY, (max_pfn << PAGE_SHIFT) + offset, 0, 0, 0);
-}
-
static void lg_set_status(struct virtio_device *vdev, u8 status)
{
BUG_ON(!status);
- set_status(vdev, status);
+ to_lgdev(vdev)->desc->status = status;
+
+ /* Tell Host immediately if we failed. */
+ if (status & VIRTIO_CONFIG_S_FAILED)
+ status_notify(vdev);
}
static void lg_reset(struct virtio_device *vdev)
{
- set_status(vdev, 0);
+ /* 0 status means "reset" */
+ to_lgdev(vdev)->desc->status = 0;
+ status_notify(vdev);
}
/*
diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
index 948c547..f97e625 100644
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -1,8 +1,10 @@
-/*P:200 This contains all the /dev/lguest code, whereby the userspace launcher
- * controls and communicates with the Guest. For example, the first write will
- * tell us the Guest's memory layout and entry point. A read will run the
- * Guest until something happens, such as a signal or the Guest doing a NOTIFY
- * out to the Launcher.
+/*P:200 This contains all the /dev/lguest code, whereby the userspace
+ * launcher controls and communicates with the Guest. For example,
+ * the first write will tell us the Guest's memory layout and entry
+ * point. A read will run the Guest until something happens, such as
+ * a signal or the Guest doing a NOTIFY out to the Launcher. There is
+ * also a way for the Launcher to attach eventfds to particular NOTIFY
+ * values instead of returning from the read() call.
:*/
#include <linux/uaccess.h>
#include <linux/miscdevice.h>
@@ -357,8 +359,8 @@
goto free_eventfds;
/*
- * Initialize the Guest's shadow page tables, using the toplevel
- * address the Launcher gave us. This allocates memory, so can fail.
+ * Initialize the Guest's shadow page tables. This allocates
+ * memory, so can fail.
*/
err = init_guest_pagetable(lg);
if (err)
@@ -516,6 +518,7 @@
.read = read,
.llseek = default_llseek,
};
+/*:*/
/*
* This is a textbook example of a "misc" character device. Populate a "struct
diff --git a/drivers/lguest/page_tables.c b/drivers/lguest/page_tables.c
index d21578e..3b62be16 100644
--- a/drivers/lguest/page_tables.c
+++ b/drivers/lguest/page_tables.c
@@ -17,7 +17,6 @@
#include <linux/percpu.h>
#include <asm/tlbflush.h>
#include <asm/uaccess.h>
-#include <asm/bootparam.h>
#include "lg.h"
/*M:008
@@ -156,7 +155,7 @@
}
/*
- * These functions are just like the above two, except they access the Guest
+ * These functions are just like the above, except they access the Guest
* page tables. Hence they return a Guest address.
*/
static unsigned long gpgd_addr(struct lg_cpu *cpu, unsigned long vaddr)
@@ -196,7 +195,7 @@
#endif
/*:*/
-/*M:014
+/*M:007
* get_pfn is slow: we could probably try to grab batches of pages here as
* an optimization (ie. pre-faulting).
:*/
@@ -325,10 +324,15 @@
#endif
/* First step: get the top-level Guest page table entry. */
- gpgd = lgread(cpu, gpgd_addr(cpu, vaddr), pgd_t);
- /* Toplevel not present? We can't map it in. */
- if (!(pgd_flags(gpgd) & _PAGE_PRESENT))
- return false;
+ if (unlikely(cpu->linear_pages)) {
+ /* Faking up a linear mapping. */
+ gpgd = __pgd(CHECK_GPGD_MASK);
+ } else {
+ gpgd = lgread(cpu, gpgd_addr(cpu, vaddr), pgd_t);
+ /* Toplevel not present? We can't map it in. */
+ if (!(pgd_flags(gpgd) & _PAGE_PRESENT))
+ return false;
+ }
/* Now look at the matching shadow entry. */
spgd = spgd_addr(cpu, cpu->cpu_pgd, vaddr);
@@ -353,10 +357,15 @@
}
#ifdef CONFIG_X86_PAE
- gpmd = lgread(cpu, gpmd_addr(gpgd, vaddr), pmd_t);
- /* Middle level not present? We can't map it in. */
- if (!(pmd_flags(gpmd) & _PAGE_PRESENT))
- return false;
+ if (unlikely(cpu->linear_pages)) {
+ /* Faking up a linear mapping. */
+ gpmd = __pmd(_PAGE_TABLE);
+ } else {
+ gpmd = lgread(cpu, gpmd_addr(gpgd, vaddr), pmd_t);
+ /* Middle level not present? We can't map it in. */
+ if (!(pmd_flags(gpmd) & _PAGE_PRESENT))
+ return false;
+ }
/* Now look at the matching shadow entry. */
spmd = spmd_addr(cpu, *spgd, vaddr);
@@ -397,8 +406,13 @@
gpte_ptr = gpte_addr(cpu, gpgd, vaddr);
#endif
- /* Read the actual PTE value. */
- gpte = lgread(cpu, gpte_ptr, pte_t);
+ if (unlikely(cpu->linear_pages)) {
+ /* Linear? Make up a PTE which points to same page. */
+ gpte = __pte((vaddr & PAGE_MASK) | _PAGE_RW | _PAGE_PRESENT);
+ } else {
+ /* Read the actual PTE value. */
+ gpte = lgread(cpu, gpte_ptr, pte_t);
+ }
/* If this page isn't in the Guest page tables, we can't page it in. */
if (!(pte_flags(gpte) & _PAGE_PRESENT))
@@ -454,7 +468,8 @@
* Finally, we write the Guest PTE entry back: we've set the
* _PAGE_ACCESSED and maybe the _PAGE_DIRTY flags.
*/
- lgwrite(cpu, gpte_ptr, pte_t, gpte);
+ if (likely(!cpu->linear_pages))
+ lgwrite(cpu, gpte_ptr, pte_t, gpte);
/*
* The fault is fixed, the page table is populated, the mapping
@@ -612,6 +627,11 @@
#ifdef CONFIG_X86_PAE
pmd_t gpmd;
#endif
+
+ /* Still not set up? Just map 1:1. */
+ if (unlikely(cpu->linear_pages))
+ return vaddr;
+
/* First step: get the top-level Guest page table entry. */
gpgd = lgread(cpu, gpgd_addr(cpu, vaddr), pgd_t);
/* Toplevel not present? We can't map it in. */
@@ -708,32 +728,6 @@
return next;
}
-/*H:430
- * (iv) Switching page tables
- *
- * Now we've seen all the page table setting and manipulation, let's see
- * what happens when the Guest changes page tables (ie. changes the top-level
- * pgdir). This occurs on almost every context switch.
- */
-void guest_new_pagetable(struct lg_cpu *cpu, unsigned long pgtable)
-{
- int newpgdir, repin = 0;
-
- /* Look to see if we have this one already. */
- newpgdir = find_pgdir(cpu->lg, pgtable);
- /*
- * If not, we allocate or mug an existing one: if it's a fresh one,
- * repin gets set to 1.
- */
- if (newpgdir == ARRAY_SIZE(cpu->lg->pgdirs))
- newpgdir = new_pgdir(cpu, pgtable, &repin);
- /* Change the current pgd index to the new one. */
- cpu->cpu_pgd = newpgdir;
- /* If it was completely blank, we map in the Guest kernel stack */
- if (repin)
- pin_stack_pages(cpu);
-}
-
/*H:470
* Finally, a routine which throws away everything: all PGD entries in all
* the shadow page tables, including the Guest's kernel mappings. This is used
@@ -780,6 +774,44 @@
/* We need the Guest kernel stack mapped again. */
pin_stack_pages(cpu);
}
+
+/*H:430
+ * (iv) Switching page tables
+ *
+ * Now we've seen all the page table setting and manipulation, let's see
+ * what happens when the Guest changes page tables (ie. changes the top-level
+ * pgdir). This occurs on almost every context switch.
+ */
+void guest_new_pagetable(struct lg_cpu *cpu, unsigned long pgtable)
+{
+ int newpgdir, repin = 0;
+
+ /*
+ * The very first time they call this, we're actually running without
+ * any page tables; we've been making it up. Throw them away now.
+ */
+ if (unlikely(cpu->linear_pages)) {
+ release_all_pagetables(cpu->lg);
+ cpu->linear_pages = false;
+ /* Force allocation of a new pgdir. */
+ newpgdir = ARRAY_SIZE(cpu->lg->pgdirs);
+ } else {
+ /* Look to see if we have this one already. */
+ newpgdir = find_pgdir(cpu->lg, pgtable);
+ }
+
+ /*
+ * If not, we allocate or mug an existing one: if it's a fresh one,
+ * repin gets set to 1.
+ */
+ if (newpgdir == ARRAY_SIZE(cpu->lg->pgdirs))
+ newpgdir = new_pgdir(cpu, pgtable, &repin);
+ /* Change the current pgd index to the new one. */
+ cpu->cpu_pgd = newpgdir;
+ /* If it was completely blank, we map in the Guest kernel stack */
+ if (repin)
+ pin_stack_pages(cpu);
+}
/*:*/
/*M:009
@@ -919,168 +951,26 @@
}
#endif
-/*H:505
- * To get through boot, we construct simple identity page mappings (which
- * set virtual == physical) and linear mappings which will get the Guest far
- * enough into the boot to create its own. The linear mapping means we
- * simplify the Guest boot, but it makes assumptions about their PAGE_OFFSET,
- * as you'll see.
- *
- * We lay them out of the way, just below the initrd (which is why we need to
- * know its size here).
- */
-static unsigned long setup_pagetables(struct lguest *lg,
- unsigned long mem,
- unsigned long initrd_size)
-{
- pgd_t __user *pgdir;
- pte_t __user *linear;
- unsigned long mem_base = (unsigned long)lg->mem_base;
- unsigned int mapped_pages, i, linear_pages;
-#ifdef CONFIG_X86_PAE
- pmd_t __user *pmds;
- unsigned int j;
- pgd_t pgd;
- pmd_t pmd;
-#else
- unsigned int phys_linear;
-#endif
-
- /*
- * We have mapped_pages frames to map, so we need linear_pages page
- * tables to map them.
- */
- mapped_pages = mem / PAGE_SIZE;
- linear_pages = (mapped_pages + PTRS_PER_PTE - 1) / PTRS_PER_PTE;
-
- /* We put the toplevel page directory page at the top of memory. */
- pgdir = (pgd_t *)(mem + mem_base - initrd_size - PAGE_SIZE);
-
- /* Now we use the next linear_pages pages as pte pages */
- linear = (void *)pgdir - linear_pages * PAGE_SIZE;
-
-#ifdef CONFIG_X86_PAE
- /*
- * And the single mid page goes below that. We only use one, but
- * that's enough to map 1G, which definitely gets us through boot.
- */
- pmds = (void *)linear - PAGE_SIZE;
-#endif
- /*
- * Linear mapping is easy: put every page's address into the
- * mapping in order.
- */
- for (i = 0; i < mapped_pages; i++) {
- pte_t pte;
- pte = pfn_pte(i, __pgprot(_PAGE_PRESENT|_PAGE_RW|_PAGE_USER));
- if (copy_to_user(&linear[i], &pte, sizeof(pte)) != 0)
- return -EFAULT;
- }
-
-#ifdef CONFIG_X86_PAE
- /*
- * Make the Guest PMD entries point to the corresponding place in the
- * linear mapping (up to one page worth of PMD).
- */
- for (i = j = 0; i < mapped_pages && j < PTRS_PER_PMD;
- i += PTRS_PER_PTE, j++) {
- pmd = pfn_pmd(((unsigned long)&linear[i] - mem_base)/PAGE_SIZE,
- __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER));
-
- if (copy_to_user(&pmds[j], &pmd, sizeof(pmd)) != 0)
- return -EFAULT;
- }
-
- /* One PGD entry, pointing to that PMD page. */
- pgd = __pgd(((unsigned long)pmds - mem_base) | _PAGE_PRESENT);
- /* Copy it in as the first PGD entry (ie. addresses 0-1G). */
- if (copy_to_user(&pgdir[0], &pgd, sizeof(pgd)) != 0)
- return -EFAULT;
- /*
- * And the other PGD entry to make the linear mapping at PAGE_OFFSET
- */
- if (copy_to_user(&pgdir[KERNEL_PGD_BOUNDARY], &pgd, sizeof(pgd)))
- return -EFAULT;
-#else
- /*
- * The top level points to the linear page table pages above.
- * We setup the identity and linear mappings here.
- */
- phys_linear = (unsigned long)linear - mem_base;
- for (i = 0; i < mapped_pages; i += PTRS_PER_PTE) {
- pgd_t pgd;
- /*
- * Create a PGD entry which points to the right part of the
- * linear PTE pages.
- */
- pgd = __pgd((phys_linear + i * sizeof(pte_t)) |
- (_PAGE_PRESENT | _PAGE_RW | _PAGE_USER));
-
- /*
- * Copy it into the PGD page at 0 and PAGE_OFFSET.
- */
- if (copy_to_user(&pgdir[i / PTRS_PER_PTE], &pgd, sizeof(pgd))
- || copy_to_user(&pgdir[pgd_index(PAGE_OFFSET)
- + i / PTRS_PER_PTE],
- &pgd, sizeof(pgd)))
- return -EFAULT;
- }
-#endif
-
- /*
- * We return the top level (guest-physical) address: we remember where
- * this is to write it into lguest_data when the Guest initializes.
- */
- return (unsigned long)pgdir - mem_base;
-}
-
/*H:500
* (vii) Setting up the page tables initially.
*
- * When a Guest is first created, the Launcher tells us where the toplevel of
- * its first page table is. We set some things up here:
+ * When a Guest is first created, set initialize a shadow page table which
+ * we will populate on future faults. The Guest doesn't have any actual
+ * pagetables yet, so we set linear_pages to tell demand_page() to fake it
+ * for the moment.
*/
int init_guest_pagetable(struct lguest *lg)
{
- u64 mem;
- u32 initrd_size;
- struct boot_params __user *boot = (struct boot_params *)lg->mem_base;
-#ifdef CONFIG_X86_PAE
- pgd_t *pgd;
- pmd_t *pmd_table;
-#endif
- /*
- * Get the Guest memory size and the ramdisk size from the boot header
- * located at lg->mem_base (Guest address 0).
- */
- if (copy_from_user(&mem, &boot->e820_map[0].size, sizeof(mem))
- || get_user(initrd_size, &boot->hdr.ramdisk_size))
- return -EFAULT;
+ struct lg_cpu *cpu = &lg->cpus[0];
+ int allocated = 0;
- /*
- * We start on the first shadow page table, and give it a blank PGD
- * page.
- */
- lg->pgdirs[0].gpgdir = setup_pagetables(lg, mem, initrd_size);
- if (IS_ERR_VALUE(lg->pgdirs[0].gpgdir))
- return lg->pgdirs[0].gpgdir;
- lg->pgdirs[0].pgdir = (pgd_t *)get_zeroed_page(GFP_KERNEL);
- if (!lg->pgdirs[0].pgdir)
+ /* lg (and lg->cpus[]) starts zeroed: this allocates a new pgdir */
+ cpu->cpu_pgd = new_pgdir(cpu, 0, &allocated);
+ if (!allocated)
return -ENOMEM;
-#ifdef CONFIG_X86_PAE
- /* For PAE, we also create the initial mid-level. */
- pgd = lg->pgdirs[0].pgdir;
- pmd_table = (pmd_t *) get_zeroed_page(GFP_KERNEL);
- if (!pmd_table)
- return -ENOMEM;
-
- set_pgd(pgd + SWITCHER_PGD_INDEX,
- __pgd(__pa(pmd_table) | _PAGE_PRESENT));
-#endif
-
- /* This is the current page table. */
- lg->cpus[0].cpu_pgd = 0;
+ /* We start with a linear mapping until the initialize. */
+ cpu->linear_pages = true;
return 0;
}
@@ -1095,10 +985,10 @@
* of virtual addresses used by the Switcher.
*/
|| put_user(RESERVE_MEM * 1024 * 1024,
- &cpu->lg->lguest_data->reserve_mem)
- || put_user(cpu->lg->pgdirs[0].gpgdir,
- &cpu->lg->lguest_data->pgdir))
+ &cpu->lg->lguest_data->reserve_mem)) {
kill_guest(cpu, "bad guest page %p", cpu->lg->lguest_data);
+ return;
+ }
/*
* In flush_user_mappings() we loop from 0 to
diff --git a/drivers/lguest/x86/core.c b/drivers/lguest/x86/core.c
index 9f1659c..65af42f 100644
--- a/drivers/lguest/x86/core.c
+++ b/drivers/lguest/x86/core.c
@@ -269,10 +269,10 @@
static int emulate_insn(struct lg_cpu *cpu)
{
u8 insn;
- unsigned int insnlen = 0, in = 0, shift = 0;
+ unsigned int insnlen = 0, in = 0, small_operand = 0;
/*
* The eip contains the *virtual* address of the Guest's instruction:
- * guest_pa just subtracts the Guest's page_offset.
+ * walk the Guest's page tables to find the "physical" address.
*/
unsigned long physaddr = guest_pa(cpu, cpu->regs->eip);
@@ -300,11 +300,10 @@
}
/*
- * 0x66 is an "operand prefix". It means it's using the upper 16 bits
- * of the eax register.
+ * 0x66 is an "operand prefix". It means a 16, not 32 bit in/out.
*/
if (insn == 0x66) {
- shift = 16;
+ small_operand = 1;
/* The instruction is 1 byte so far, read the next byte. */
insnlen = 1;
insn = lgread(cpu, physaddr + insnlen, u8);
@@ -340,11 +339,14 @@
* traditionally means "there's nothing there".
*/
if (in) {
- /* Lower bit tells is whether it's a 16 or 32 bit access */
- if (insn & 0x1)
- cpu->regs->eax = 0xFFFFFFFF;
- else
- cpu->regs->eax |= (0xFFFF << shift);
+ /* Lower bit tells means it's a 32/16 bit access */
+ if (insn & 0x1) {
+ if (small_operand)
+ cpu->regs->eax |= 0xFFFF;
+ else
+ cpu->regs->eax = 0xFFFFFFFF;
+ } else
+ cpu->regs->eax |= 0xFF;
}
/* Finally, we've "done" the instruction, so move past it. */
cpu->regs->eip += insnlen;
@@ -352,69 +354,6 @@
return 1;
}
-/*
- * Our hypercalls mechanism used to be based on direct software interrupts.
- * After Anthony's "Refactor hypercall infrastructure" kvm patch, we decided to
- * change over to using kvm hypercalls.
- *
- * KVM_HYPERCALL is actually a "vmcall" instruction, which generates an invalid
- * opcode fault (fault 6) on non-VT cpus, so the easiest solution seemed to be
- * an *emulation approach*: if the fault was really produced by an hypercall
- * (is_hypercall() does exactly this check), we can just call the corresponding
- * hypercall host implementation function.
- *
- * But these invalid opcode faults are notably slower than software interrupts.
- * So we implemented the *patching (or rewriting) approach*: every time we hit
- * the KVM_HYPERCALL opcode in Guest code, we patch it to the old "int 0x1f"
- * opcode, so next time the Guest calls this hypercall it will use the
- * faster trap mechanism.
- *
- * Matias even benchmarked it to convince you: this shows the average cycle
- * cost of a hypercall. For each alternative solution mentioned above we've
- * made 5 runs of the benchmark:
- *
- * 1) direct software interrupt: 2915, 2789, 2764, 2721, 2898
- * 2) emulation technique: 3410, 3681, 3466, 3392, 3780
- * 3) patching (rewrite) technique: 2977, 2975, 2891, 2637, 2884
- *
- * One two-line function is worth a 20% hypercall speed boost!
- */
-static void rewrite_hypercall(struct lg_cpu *cpu)
-{
- /*
- * This are the opcodes we use to patch the Guest. The opcode for "int
- * $0x1f" is "0xcd 0x1f" but vmcall instruction is 3 bytes long, so we
- * complete the sequence with a NOP (0x90).
- */
- u8 insn[3] = {0xcd, 0x1f, 0x90};
-
- __lgwrite(cpu, guest_pa(cpu, cpu->regs->eip), insn, sizeof(insn));
- /*
- * The above write might have caused a copy of that page to be made
- * (if it was read-only). We need to make sure the Guest has
- * up-to-date pagetables. As this doesn't happen often, we can just
- * drop them all.
- */
- guest_pagetable_clear_all(cpu);
-}
-
-static bool is_hypercall(struct lg_cpu *cpu)
-{
- u8 insn[3];
-
- /*
- * This must be the Guest kernel trying to do something.
- * The bottom two bits of the CS segment register are the privilege
- * level.
- */
- if ((cpu->regs->cs & 3) != GUEST_PL)
- return false;
-
- /* Is it a vmcall? */
- __lgread(cpu, insn, guest_pa(cpu, cpu->regs->eip), sizeof(insn));
- return insn[0] == 0x0f && insn[1] == 0x01 && insn[2] == 0xc1;
-}
-
/*H:050 Once we've re-enabled interrupts, we look at why the Guest exited. */
void lguest_arch_handle_trap(struct lg_cpu *cpu)
{
@@ -429,20 +368,6 @@
if (emulate_insn(cpu))
return;
}
- /*
- * If KVM is active, the vmcall instruction triggers a General
- * Protection Fault. Normally it triggers an invalid opcode
- * fault (6):
- */
- case 6:
- /*
- * We need to check if ring == GUEST_PL and faulting
- * instruction == vmcall.
- */
- if (is_hypercall(cpu)) {
- rewrite_hypercall(cpu);
- return;
- }
break;
case 14: /* We've intercepted a Page Fault. */
/*
@@ -486,7 +411,7 @@
* These values mean a real interrupt occurred, in which case
* the Host handler has already been run. We just do a
* friendly check if another process should now be run, then
- * return to run the Guest again
+ * return to run the Guest again.
*/
cond_resched();
return;
@@ -536,7 +461,7 @@
int i;
/*
- * Most of the i386/switcher.S doesn't care that it's been moved; on
+ * Most of the x86/switcher_32.S doesn't care that it's been moved; on
* Intel, jumps are relative, and it doesn't access any references to
* external code or data.
*
@@ -664,7 +589,7 @@
clear_cpu_cap(&boot_cpu_data, X86_FEATURE_PGE);
}
put_online_cpus();
-};
+}
/*:*/
void __exit lguest_arch_host_fini(void)
@@ -747,8 +672,6 @@
/*:*/
/*L:030
- * lguest_arch_setup_regs()
- *
* Most of the Guest's registers are left alone: we used get_zeroed_page() to
* allocate the structure, so they will be 0.
*/
diff --git a/include/linux/lguest.h b/include/linux/lguest.h
index 2fb1dcb..9962c6b 100644
--- a/include/linux/lguest.h
+++ b/include/linux/lguest.h
@@ -59,8 +59,6 @@
unsigned long reserve_mem;
/* KHz for the TSC clock. */
u32 tsc_khz;
- /* Page where the top-level pagetable is */
- unsigned long pgdir;
/* Fields initialized by the Guest at boot: */
/* Instruction range to suppress interrupts even if enabled */