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| author | Kai Huang <kai.huang@linux.intel.com> | 2015-01-09 16:44:30 +0800 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2015-01-09 10:23:55 +0100 |
| commit | 7e71a59b250330fd52ee7293eb9d31952f16682e (patch) | |
| tree | 65d42aee4577a6ff7ae14ecf02816b20c532fc3f /arch/x86/kvm | |
| parent | defcf51fa93929bd5d3ce5b91f8e6a106dae5e46 (diff) | |
| download | linux-7e71a59b250330fd52ee7293eb9d31952f16682e.tar.bz2 | |
KVM: x86: flush TLB when D bit is manually changed.
When software changes D bit (either from 1 to 0, or 0 to 1), the
corresponding TLB entity in the hardware won't be updated immediately. We
should flush it to guarantee the consistence of D bit between TLB and
MMU page table in memory. This is especially important when clearing
the D bit, since it may cause false negatives in reporting dirtiness.
Sanity test was done on my machine with Intel processor.
Signed-off-by: Kai Huang <kai.huang@linux.intel.com>
[Check A bit too. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm')
| -rw-r--r-- | arch/x86/kvm/mmu.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index a0985ebb5512..0d0fdd6f002c 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -532,6 +532,11 @@ static bool spte_is_bit_cleared(u64 old_spte, u64 new_spte, u64 bit_mask) return (old_spte & bit_mask) && !(new_spte & bit_mask); } +static bool spte_is_bit_changed(u64 old_spte, u64 new_spte, u64 bit_mask) +{ + return (old_spte & bit_mask) != (new_spte & bit_mask); +} + /* Rules for using mmu_spte_set: * Set the sptep from nonpresent to present. * Note: the sptep being assigned *must* be either not present @@ -582,6 +587,14 @@ static bool mmu_spte_update(u64 *sptep, u64 new_spte) if (!shadow_accessed_mask) return ret; + /* + * Flush TLB when accessed/dirty bits are changed in the page tables, + * to guarantee consistency between TLB and page tables. + */ + if (spte_is_bit_changed(old_spte, new_spte, + shadow_accessed_mask | shadow_dirty_mask)) + ret = true; + if (spte_is_bit_cleared(old_spte, new_spte, shadow_accessed_mask)) kvm_set_pfn_accessed(spte_to_pfn(old_spte)); if (spte_is_bit_cleared(old_spte, new_spte, shadow_dirty_mask)) |