diff options
| author | Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> | 2014-04-17 05:06:16 -0400 |
|---|---|---|
| committer | Marcelo Tosatti <mtosatti@redhat.com> | 2014-04-23 16:49:52 -0400 |
| commit | 198c74f43f0f5473f99967aead30ddc622804bc1 (patch) | |
| tree | aac35e7d0e127e2a553282a686085b000d786791 /arch/x86/kvm/mmu.c | |
| parent | 7f31c9595e3c87f68dc54b3269e900f3017ed405 (diff) | |
KVM: MMU: flush tlb out of mmu lock when write-protect the sptes
Now we can flush all the TLBs out of the mmu lock without TLB corruption when
write-proect the sptes, it is because:
- we have marked large sptes readonly instead of dropping them that means we
just change the spte from writable to readonly so that we only need to care
the case of changing spte from present to present (changing the spte from
present to nonpresent will flush all the TLBs immediately), in other words,
the only case we need to care is mmu_spte_update()
- in mmu_spte_update(), we haved checked
SPTE_HOST_WRITEABLE | PTE_MMU_WRITEABLE instead of PT_WRITABLE_MASK, that
means it does not depend on PT_WRITABLE_MASK anymore
Acked-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Diffstat (limited to 'arch/x86/kvm/mmu.c')
| -rw-r--r-- | arch/x86/kvm/mmu.c | 25 |
1 files changed, 21 insertions, 4 deletions
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 388a2ef83911..65f2400b8268 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c | |||
| @@ -4309,15 +4309,32 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot) | |||
| 4309 | if (*rmapp) | 4309 | if (*rmapp) |
| 4310 | __rmap_write_protect(kvm, rmapp, false); | 4310 | __rmap_write_protect(kvm, rmapp, false); |
| 4311 | 4311 | ||
| 4312 | if (need_resched() || spin_needbreak(&kvm->mmu_lock)) { | 4312 | if (need_resched() || spin_needbreak(&kvm->mmu_lock)) |
| 4313 | kvm_flush_remote_tlbs(kvm); | ||
| 4314 | cond_resched_lock(&kvm->mmu_lock); | 4313 | cond_resched_lock(&kvm->mmu_lock); |
| 4315 | } | ||
| 4316 | } | 4314 | } |
| 4317 | } | 4315 | } |
| 4318 | 4316 | ||
| 4319 | kvm_flush_remote_tlbs(kvm); | ||
| 4320 | spin_unlock(&kvm->mmu_lock); | 4317 | spin_unlock(&kvm->mmu_lock); |
| 4318 | |||
| 4319 | /* | ||
| 4320 | * kvm_mmu_slot_remove_write_access() and kvm_vm_ioctl_get_dirty_log() | ||
| 4321 | * which do tlb flush out of mmu-lock should be serialized by | ||
| 4322 | * kvm->slots_lock otherwise tlb flush would be missed. | ||
| 4323 | */ | ||
| 4324 | lockdep_assert_held(&kvm->slots_lock); | ||
| 4325 | |||
| 4326 | /* | ||
| 4327 | * We can flush all the TLBs out of the mmu lock without TLB | ||
| 4328 | * corruption since we just change the spte from writable to | ||
| 4329 | * readonly so that we only need to care the case of changing | ||
| 4330 | * spte from present to present (changing the spte from present | ||
| 4331 | * to nonpresent will flush all the TLBs immediately), in other | ||
| 4332 | * words, the only case we care is mmu_spte_update() where we | ||
| 4333 | * haved checked SPTE_HOST_WRITEABLE | SPTE_MMU_WRITEABLE | ||
| 4334 | * instead of PT_WRITABLE_MASK, that means it does not depend | ||
| 4335 | * on PT_WRITABLE_MASK anymore. | ||
| 4336 | */ | ||
| 4337 | kvm_flush_remote_tlbs(kvm); | ||
| 4321 | } | 4338 | } |
| 4322 | 4339 | ||
| 4323 | #define BATCH_ZAP_PAGES 10 | 4340 | #define BATCH_ZAP_PAGES 10 |