xen: SMP guest support
This is a fairly straightforward Xen implementation of smp_ops.
Xen has its own IPI mechanisms, and has no dependency on any
APIC-based IPI. The smp_ops hooks and the flush_tlb_others pv_op
allow a Xen guest to avoid all APIC code in arch/i386 (the only apic
operation is a single apic_read for the apic version number).
One subtle point which needs to be addressed is unpinning pagetables
when another cpu may have a lazy tlb reference to the pagetable. Xen
will not allow an in-use pagetable to be unpinned, so we must find any
other cpus with a reference to the pagetable and get them to shoot
down their references.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Andi Kleen <ak@suse.de>
diff --git a/arch/i386/xen/enlighten.c b/arch/i386/xen/enlighten.c
index a9ba834..de62d66 100644
--- a/arch/i386/xen/enlighten.c
+++ b/arch/i386/xen/enlighten.c
@@ -24,6 +24,7 @@
#include <linux/mm.h>
#include <linux/page-flags.h>
#include <linux/highmem.h>
+#include <linux/smp.h>
#include <xen/interface/xen.h>
#include <xen/interface/physdev.h>
@@ -40,6 +41,7 @@
#include <asm/setup.h>
#include <asm/desc.h>
#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
#include "xen-ops.h"
#include "mmu.h"
@@ -56,7 +58,7 @@
struct start_info *xen_start_info;
EXPORT_SYMBOL_GPL(xen_start_info);
-static void xen_vcpu_setup(int cpu)
+void xen_vcpu_setup(int cpu)
{
per_cpu(xen_vcpu, cpu) = &HYPERVISOR_shared_info->vcpu_info[cpu];
}
@@ -347,23 +349,14 @@
}
}
-/* Load a new IDT into Xen. In principle this can be per-CPU, so we
- hold a spinlock to protect the static traps[] array (static because
- it avoids allocation, and saves stack space). */
-static void xen_load_idt(const struct Xgt_desc_struct *desc)
+static void xen_convert_trap_info(const struct Xgt_desc_struct *desc,
+ struct trap_info *traps)
{
- static DEFINE_SPINLOCK(lock);
- static struct trap_info traps[257];
-
- int cpu = smp_processor_id();
unsigned in, out, count;
- per_cpu(idt_desc, cpu) = *desc;
-
count = (desc->size+1) / 8;
BUG_ON(count > 256);
- spin_lock(&lock);
for (in = out = 0; in < count; in++) {
const u32 *entry = (u32 *)(desc->address + in * 8);
@@ -371,6 +364,31 @@
out++;
}
traps[out].address = 0;
+}
+
+void xen_copy_trap_info(struct trap_info *traps)
+{
+ const struct Xgt_desc_struct *desc = &get_cpu_var(idt_desc);
+
+ xen_convert_trap_info(desc, traps);
+
+ put_cpu_var(idt_desc);
+}
+
+/* Load a new IDT into Xen. In principle this can be per-CPU, so we
+ hold a spinlock to protect the static traps[] array (static because
+ it avoids allocation, and saves stack space). */
+static void xen_load_idt(const struct Xgt_desc_struct *desc)
+{
+ static DEFINE_SPINLOCK(lock);
+ static struct trap_info traps[257];
+ int cpu = smp_processor_id();
+
+ per_cpu(idt_desc, cpu) = *desc;
+
+ spin_lock(&lock);
+
+ xen_convert_trap_info(desc, traps);
xen_mc_flush();
if (HYPERVISOR_set_trap_table(traps))
@@ -428,6 +446,12 @@
{
return 0;
}
+
+static void xen_apic_write(unsigned long reg, unsigned long val)
+{
+ /* Warn to see if there's any stray references */
+ WARN_ON(1);
+}
#endif
static void xen_flush_tlb(void)
@@ -449,6 +473,40 @@
BUG();
}
+static void xen_flush_tlb_others(const cpumask_t *cpus, struct mm_struct *mm,
+ unsigned long va)
+{
+ struct mmuext_op op;
+ cpumask_t cpumask = *cpus;
+
+ /*
+ * A couple of (to be removed) sanity checks:
+ *
+ * - current CPU must not be in mask
+ * - mask must exist :)
+ */
+ BUG_ON(cpus_empty(cpumask));
+ BUG_ON(cpu_isset(smp_processor_id(), cpumask));
+ BUG_ON(!mm);
+
+ /* If a CPU which we ran on has gone down, OK. */
+ cpus_and(cpumask, cpumask, cpu_online_map);
+ if (cpus_empty(cpumask))
+ return;
+
+ if (va == TLB_FLUSH_ALL) {
+ op.cmd = MMUEXT_TLB_FLUSH_MULTI;
+ op.arg2.vcpumask = (void *)cpus;
+ } else {
+ op.cmd = MMUEXT_INVLPG_MULTI;
+ op.arg1.linear_addr = va;
+ op.arg2.vcpumask = (void *)cpus;
+ }
+
+ if (HYPERVISOR_mmuext_op(&op, 1, NULL, DOMID_SELF))
+ BUG();
+}
+
static unsigned long xen_read_cr2(void)
{
return x86_read_percpu(xen_vcpu)->arch.cr2;
@@ -460,18 +518,6 @@
native_write_cr4(cr4 & ~X86_CR4_TSD);
}
-/*
- * Page-directory addresses above 4GB do not fit into architectural %cr3.
- * When accessing %cr3, or equivalent field in vcpu_guest_context, guests
- * must use the following accessor macros to pack/unpack valid MFNs.
- *
- * Note that Xen is using the fact that the pagetable base is always
- * page-aligned, and putting the 12 MSB of the address into the 12 LSB
- * of cr3.
- */
-#define xen_pfn_to_cr3(pfn) (((unsigned)(pfn) << 12) | ((unsigned)(pfn) >> 20))
-#define xen_cr3_to_pfn(cr3) (((unsigned)(cr3) >> 12) | ((unsigned)(cr3) << 20))
-
static unsigned long xen_read_cr3(void)
{
return x86_read_percpu(xen_cr3);
@@ -740,8 +786,8 @@
.io_delay = xen_io_delay,
#ifdef CONFIG_X86_LOCAL_APIC
- .apic_write = paravirt_nop,
- .apic_write_atomic = paravirt_nop,
+ .apic_write = xen_apic_write,
+ .apic_write_atomic = xen_apic_write,
.apic_read = xen_apic_read,
.setup_boot_clock = paravirt_nop,
.setup_secondary_clock = paravirt_nop,
@@ -751,6 +797,7 @@
.flush_tlb_user = xen_flush_tlb,
.flush_tlb_kernel = xen_flush_tlb,
.flush_tlb_single = xen_flush_tlb_single,
+ .flush_tlb_others = xen_flush_tlb_others,
.pte_update = paravirt_nop,
.pte_update_defer = paravirt_nop,
@@ -796,6 +843,19 @@
.set_lazy_mode = xen_set_lazy_mode,
};
+#ifdef CONFIG_SMP
+static const struct smp_ops xen_smp_ops __initdata = {
+ .smp_prepare_boot_cpu = xen_smp_prepare_boot_cpu,
+ .smp_prepare_cpus = xen_smp_prepare_cpus,
+ .cpu_up = xen_cpu_up,
+ .smp_cpus_done = xen_smp_cpus_done,
+
+ .smp_send_stop = xen_smp_send_stop,
+ .smp_send_reschedule = xen_smp_send_reschedule,
+ .smp_call_function_mask = xen_smp_call_function_mask,
+};
+#endif /* CONFIG_SMP */
+
/* First C function to be called on Xen boot */
asmlinkage void __init xen_start_kernel(void)
{
@@ -808,6 +868,9 @@
/* Install Xen paravirt ops */
paravirt_ops = xen_paravirt_ops;
+#ifdef CONFIG_SMP
+ smp_ops = xen_smp_ops;
+#endif
xen_setup_features();