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Message-Id: <1216123958-10717-20-git-send-email-avi@qumranet.com> Date: Tue, 15 Jul 2008 15:12:38 +0300 From: Avi Kivity <avi@...ranet.com> To: kvm@...r.kernel.org Cc: linux-kernel@...r.kernel.org Subject: [PATCH 19/19] KVM: MMU: Fix potential race setting upper shadow ptes on nonpae hosts 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 <avi@...ranet.com> --- arch/x86/kvm/mmu.c | 7 ++++--- 1 files changed, 4 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 7f57da6..b0e4ddc 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -1189,9 +1189,10 @@ 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; } -- 1.5.6.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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