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authorTakuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>2013-06-21 01:34:31 +0900
committerGleb Natapov <gleb@redhat.com>2013-06-27 14:20:49 +0300
commit7a2e8aaf0f6873b47bc2347f216ea5b0e4c258ab (patch)
treef5f908921cfd899e706cb455acb91d74c9ba894f /arch/x86
parent5a9b3830d462971bf05329148873f8996d1c88fc (diff)
KVM: MMU: Inform users of mmio generation wraparound
Without this information, users will just see unexpected performance problems and there is little chance we will get good reports from them: note that mmio generation is increased even when we just start, or stop, dirty logging for some memory slot, in which case users cannot expect all shadow pages to be zapped. printk_ratelimited() is used for this taking into account the problems that we can see the information many times when we start multiple VMs and guests can trigger this by reading ROM in a loop for example. Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kvm/mmu.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index f385a4cf4bfd..0d094da49541 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -4387,8 +4387,10 @@ void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm)
* The max value is MMIO_MAX_GEN - 1 since it is not called
* when mark memslot invalid.
*/
- if (unlikely(kvm_current_mmio_generation(kvm) >= (MMIO_MAX_GEN - 1)))
+ if (unlikely(kvm_current_mmio_generation(kvm) >= (MMIO_MAX_GEN - 1))) {
+ printk_ratelimited(KERN_INFO "kvm: zapping shadow pages for mmio generation wraparound\n");
kvm_mmu_invalidate_zap_all_pages(kvm);
+ }
}
static int mmu_shrink(struct shrinker *shrink, struct shrink_control *sc)