forked from Minki/linux
KVM: x86: avoid write-tearing of TDP
In theory, nothing prevents the compiler from write-tearing PTEs, or split PTE writes. These partially-modified PTEs can be fetched by other cores and cause mayhem. I have not really encountered such case in real-life, but it does seem possible. For example, the compiler may try to do something creative for kvm_set_pte_rmapp() and perform multiple writes to the PTE. Signed-off-by: Nadav Amit <nadav.amit@gmail.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
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@ -336,12 +336,12 @@ static gfn_t pse36_gfn_delta(u32 gpte)
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#ifdef CONFIG_X86_64
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static void __set_spte(u64 *sptep, u64 spte)
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{
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*sptep = spte;
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WRITE_ONCE(*sptep, spte);
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}
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static void __update_clear_spte_fast(u64 *sptep, u64 spte)
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{
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*sptep = spte;
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WRITE_ONCE(*sptep, spte);
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}
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static u64 __update_clear_spte_slow(u64 *sptep, u64 spte)
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@ -390,7 +390,7 @@ static void __set_spte(u64 *sptep, u64 spte)
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*/
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smp_wmb();
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ssptep->spte_low = sspte.spte_low;
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WRITE_ONCE(ssptep->spte_low, sspte.spte_low);
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}
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static void __update_clear_spte_fast(u64 *sptep, u64 spte)
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@ -400,7 +400,7 @@ static void __update_clear_spte_fast(u64 *sptep, u64 spte)
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ssptep = (union split_spte *)sptep;
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sspte = (union split_spte)spte;
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ssptep->spte_low = sspte.spte_low;
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WRITE_ONCE(ssptep->spte_low, sspte.spte_low);
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/*
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* If we map the spte from present to nonpresent, we should clear
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