[PATCH 40/58] KVM: MMU: Make setting shadow ptes atomic on i386

Avi Kivity
2007-06-17T09:44:21Z

drivers/kvm/Kconfig | 1 +
drivers/kvm/mmu.c | 14 ++++++++++++--
drivers/kvm/paging_tmpl.h | 4 ++--
3 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/kvm/Kconfig b/drivers/kvm/Kconfig
index 2f661e5..33fa28a 100644
--- a/drivers/kvm/Kconfig
+++ b/drivers/kvm/Kconfig
@@ -11,6 +11,7 @@ if VIRTUALIZATION
config KVM
tristate "Kernel-based Virtual Machine (KVM) support"
depends on X86 && EXPERIMENTAL
+ depends on X86_CMPXCHG64 || 64BIT
---help---
Support hosting fully virtualized guest machines using hardware
virtualization extensions. You will need a fairly recent
diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index 3cdbf68..f24b540 100644
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -22,6 +22,7 @@
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/module.h>
+#include <asm/cmpxchg.h>

#include "vmx.h"
#include "kvm.h"
@@ -204,6 +205,15 @@ static int is_rmap_pte(u64 pte)
== (PT_WRITABLE_MASK | PT_PRESENT_MASK);
}

+static void set_shadow_pte(u64 *sptep, u64 spte)
+{
+#ifdef CONFIG_X86_64
+ set_64bit((unsigned long *)sptep, spte);
+#else
+ set_64bit((unsigned long long *)sptep, spte);
+#endif
+}
+
static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache,
struct kmem_cache *base_cache, int min,
gfp_t gfp_flags)
@@ -446,7 +456,7 @@ static void rmap_write_protect(struct kvm_vcpu *vcpu, u64 gfn)
rmap_printk("rmap_write_protect: spte %p %llx\n", spte, *spte);
rmap_remove(vcpu, spte);
kvm_arch_ops->tlb_flush(vcpu);
- *spte &= ~(u64)PT_WRITABLE_MASK;
+ set_shadow_pte(spte, *spte & ~PT_WRITABLE_MASK);
}
}

@@ -699,7 +709,7 @@ static void kvm_mmu_zap_page(struct kvm_vcpu *vcpu,
}
BUG_ON(!parent_pte);
kvm_mmu_put_page(vcpu, page, parent_pte);
- *parent_pte = 0;
+ set_shadow_pte(parent_pte, 0);
}
kvm_mmu_page_unlink_children(vcpu, page);
if (!page->root_count) {
diff --git a/drivers/kvm/paging_tmpl.h b/drivers/kvm/paging_tmpl.h
index 397a403..fabc2c9 100644
--- a/drivers/kvm/paging_tmpl.h
+++ b/drivers/kvm/paging_tmpl.h
@@ -234,7 +234,7 @@ static void FNAME(set_pte_common)(struct kvm_vcpu *vcpu,
spte |= gaddr;
spte |= PT_SHADOW_IO_MARK;
spte &= ~PT_PRESENT_MASK;
- *shadow_pte = spte;
+ set_shadow_pte(shadow_pte, spte);
return;
}

@@ -280,7 +280,7 @@ unshadowed:
if (access_bits & PT_WRITABLE_MASK)
mark_page_dirty(vcpu->kvm, gaddr >> PAGE_SHIFT);

- *shadow_pte = spte;
+ set_shadow_pte(shadow_pte, spte);
page_header_update_slot(vcpu->kvm, shadow_pte, gaddr);
if (!was_rmapped)
rmap_add(vcpu, shadow_pte);