From 8c5a4a12d8d5bf025a09a576a0b5c62e0167423c Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Wed, 23 Jul 2008 11:43:43 +0300 Subject: [PATCH] KVM: MMU: Fix potential race setting upper shadow ptes on nonpae hosts Original-Commit-Hash: c23a6fe17abf8562e675465f8d55ba1a551d314d The direct mapped shadow code (used for real mode and two dimensional paging) sets upper-level ptes using direct assignment rather than calling set_shadow_pte(). A nonpae host will split this into two writes, which opens up a race if another vcpu accesses the same memory area. Fix by calling set_shadow_pte() instead of assigning directly. Noticed by Izik Eidus. Signed-off-by: Avi Kivity Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/mmu.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index c640b2f96c86..c26d811d9191 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -1171,9 +1171,10 @@ static int __direct_map(struct kvm_vcpu *vcpu, gpa_t v, int write, return -ENOMEM; } - table[index] = __pa(new_table->spt) - | PT_PRESENT_MASK | PT_WRITABLE_MASK - | shadow_user_mask | shadow_x_mask; + set_shadow_pte(&table[index], + __pa(new_table->spt) + | PT_PRESENT_MASK | PT_WRITABLE_MASK + | shadow_user_mask | shadow_x_mask); } table_addr = table[index] & PT64_BASE_ADDR_MASK; } -- 2.34.1