diff options
author | Ben Hutchings <ben@decadent.org.uk> | 2015-10-15 01:20:29 +0100 |
---|---|---|
committer | Ben Hutchings <ben@decadent.org.uk> | 2015-11-17 15:54:40 +0000 |
commit | 005f90fa5c6bf0b7d0f08df1b0b712e7e8d92b6f (patch) | |
tree | ab43c51abb200a1a347fd3fc6cfca2977c07983a /arch | |
parent | 0149138c4142da287d23f9d5c6038f7fb5e30ac2 (diff) |
Revert "KVM: MMU: fix validation of mmio page fault"
This reverts commit 41e3025eacd6daafc40c3e7850fbcabc8b847805, which
was commit 6f691251c0350ac52a007c54bf3ef62e9d8cdc5e upstream.
The fix is only needed after commit f8f559422b6c ("KVM: MMU: fast
invalidate all mmio sptes"), included in Linux 3.11.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/x86/kvm/mmu.c | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index cac7b2b5595f..4a949c7f6423 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -326,6 +326,12 @@ static u64 __get_spte_lockless(u64 *sptep) { return ACCESS_ONCE(*sptep); } + +static bool __check_direct_spte_mmio_pf(u64 spte) +{ + /* It is valid if the spte is zapped. */ + return spte == 0ull; +} #else union split_spte { struct { @@ -430,6 +436,23 @@ retry: return spte.spte; } + +static bool __check_direct_spte_mmio_pf(u64 spte) +{ + union split_spte sspte = (union split_spte)spte; + u32 high_mmio_mask = shadow_mmio_mask >> 32; + + /* It is valid if the spte is zapped. */ + if (spte == 0ull) + return true; + + /* It is valid if the spte is being zapped. */ + if (sspte.spte_low == 0ull && + (sspte.spte_high & high_mmio_mask) == high_mmio_mask) + return true; + + return false; +} #endif static bool spte_has_volatile_bits(u64 spte) @@ -2872,6 +2895,21 @@ static bool quickly_check_mmio_pf(struct kvm_vcpu *vcpu, u64 addr, bool direct) return vcpu_match_mmio_gva(vcpu, addr); } + +/* + * On direct hosts, the last spte is only allows two states + * for mmio page fault: + * - It is the mmio spte + * - It is zapped or it is being zapped. + * + * This function completely checks the spte when the last spte + * is not the mmio spte. + */ +static bool check_direct_spte_mmio_pf(u64 spte) +{ + return __check_direct_spte_mmio_pf(spte); +} + static u64 walk_shadow_page_get_mmio_spte(struct kvm_vcpu *vcpu, u64 addr) { struct kvm_shadow_walk_iterator iterator; @@ -2913,6 +2951,13 @@ int handle_mmio_page_fault_common(struct kvm_vcpu *vcpu, u64 addr, bool direct) } /* + * It's ok if the gva is remapped by other cpus on shadow guest, + * it's a BUG if the gfn is not a mmio page. + */ + if (direct && !check_direct_spte_mmio_pf(spte)) + return -1; + + /* * If the page table is zapped by other cpus, let CPU fault again on * the address. */ |