lguest: update comments
Also removes a long-unused #define and an extraneous semicolon.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/Documentation/virtual/lguest/lguest.c b/Documentation/virtual/lguest/lguest.c
index 80261d3..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 */
@@ -1359,7 +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
@@ -1369,7 +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)
@@ -2006,10 +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/lguest/boot.c b/arch/x86/lguest/boot.c
index 719a32c..7427990 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);
@@ -640,7 +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).
*/
@@ -1139,7 +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 c8c95e5..cfa23e3 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
+ * addesses (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!
*
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 f0c1715..28433a1 100644
--- a/drivers/lguest/interrupts_and_traps.c
+++ b/drivers/lguest/interrupts_and_traps.c
@@ -427,8 +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/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 0002622..3b62be16 100644
--- a/drivers/lguest/page_tables.c
+++ b/drivers/lguest/page_tables.c
@@ -155,7 +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)
@@ -195,7 +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).
:*/
diff --git a/drivers/lguest/x86/core.c b/drivers/lguest/x86/core.c
index ec0cdfc..3b9b810 100644
--- a/drivers/lguest/x86/core.c
+++ b/drivers/lguest/x86/core.c
@@ -272,7 +272,7 @@
unsigned int insnlen = 0, in = 0, shift = 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);
@@ -409,7 +409,7 @@
* 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;
@@ -459,7 +459,7 @@
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.
*
@@ -587,7 +587,7 @@
clear_cpu_cap(&boot_cpu_data, X86_FEATURE_PGE);
}
put_online_cpus();
-};
+}
/*:*/
void __exit lguest_arch_host_fini(void)
@@ -670,8 +670,6 @@
/*:*/
/*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.
*/