From 8d2d73b9a5c35f2c6abf427afba7888cfc4cc65d Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Wed, 4 Jun 2008 18:42:24 +0300 Subject: KVM: MMU: reschedule during shadow teardown Shadows for large guests can take a long time to tear down, so reschedule occasionally to avoid softlockup warnings. Signed-off-by: Avi Kivity --- arch/x86/kvm/mmu.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/x86/kvm/mmu.c') diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 7246b60afb9..c2fd6a4a58c 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -1858,6 +1858,7 @@ static void free_mmu_pages(struct kvm_vcpu *vcpu) sp = container_of(vcpu->kvm->arch.active_mmu_pages.next, struct kvm_mmu_page, link); kvm_mmu_zap_page(vcpu->kvm, sp); + cond_resched(); } free_page((unsigned long)vcpu->arch.mmu.pae_root); } -- cgit v1.2.3 From 3c9155106d589584f67b026ec444e69c4a68d7dc Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Tue, 20 May 2008 16:21:13 +0300 Subject: KVM: MMU: Fix is_empty_shadow_page() check The check is only looking at one of two possible empty ptes. Signed-off-by: Avi Kivity --- arch/x86/kvm/mmu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/kvm/mmu.c') diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index c2fd6a4a58c..ee3f53098f0 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -658,7 +658,7 @@ static int is_empty_shadow_page(u64 *spt) u64 *end; for (pos = spt, end = pos + PAGE_SIZE / sizeof(u64); pos != end; pos++) - if (*pos != shadow_trap_nonpresent_pte) { + if (is_shadow_present_pte(*pos)) { printk(KERN_ERR "%s: %p %llx\n", __func__, pos, *pos); return 0; -- cgit v1.2.3 From 6597ca09e6c0e5aec7ffd2b8ab48c671d3c28414 Mon Sep 17 00:00:00 2001 From: Marcelo Tosatti Date: Sun, 8 Jun 2008 01:48:53 -0300 Subject: KVM: MMU: Fix rmap_write_protect() hugepage iteration bug rmap_next() does not work correctly after rmap_remove(), as it expects the rmap chains not to change during iteration. Fix (for now) by restarting iteration from the beginning. Signed-off-by: Avi Kivity --- arch/x86/kvm/mmu.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/x86/kvm/mmu.c') diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index ee3f53098f0..9628091c574 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -640,6 +640,7 @@ static void rmap_write_protect(struct kvm *kvm, u64 gfn) rmap_remove(kvm, spte); --kvm->stat.lpages; set_shadow_pte(spte, shadow_trap_nonpresent_pte); + spte = NULL; write_protected = 1; } spte = rmap_next(kvm, rmapp, spte); -- cgit v1.2.3 From 3094538739415a9225afd2a6c78cb0fe1c1f641b Mon Sep 17 00:00:00 2001 From: Marcelo Tosatti Date: Wed, 11 Jun 2008 20:32:40 -0300 Subject: KVM: MMU: large page update_pte issue with non-PAE 32-bit guests (resend) kvm_mmu_pte_write() does not handle 32-bit non-PAE large page backed guests properly. It will instantiate two 2MB sptes pointing to the same physical 2MB page when a guest large pte update is trapped. Instead of duplicating code to handle this, disallow directory level updates to happen through kvm_mmu_pte_write(), so the two 2MB sptes emulating one guest 4MB pte can be correctly created by the page fault handling path. Signed-off-by: Marcelo Tosatti Signed-off-by: Avi Kivity --- arch/x86/kvm/mmu.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) (limited to 'arch/x86/kvm/mmu.c') diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 9628091c574..baa6503894d 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -1581,11 +1581,13 @@ static void mmu_pte_write_new_pte(struct kvm_vcpu *vcpu, u64 *spte, const void *new) { - if ((sp->role.level != PT_PAGE_TABLE_LEVEL) - && !vcpu->arch.update_pte.largepage) { - ++vcpu->kvm->stat.mmu_pde_zapped; - return; - } + if (sp->role.level != PT_PAGE_TABLE_LEVEL) { + if (!vcpu->arch.update_pte.largepage || + sp->role.glevels == PT32_ROOT_LEVEL) { + ++vcpu->kvm->stat.mmu_pde_zapped; + return; + } + } ++vcpu->kvm->stat.mmu_pte_updated; if (sp->role.glevels == PT32_ROOT_LEVEL) -- cgit v1.2.3 From 6bf6a9532fd03ad719f0c86654f16ef777b78fc6 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Thu, 12 Jun 2008 16:54:41 +0300 Subject: KVM: MMU: Fix oops on guest userspace access to guest pagetable KVM has a heuristic to unshadow guest pagetables when userspace accesses them, on the assumption that most guests do not allow userspace to access pagetables directly. Unfortunately, in addition to unshadowing the pagetables, it also oopses. This never triggers on ordinary guests since sane OSes will clear the pagetables before assigning them to userspace, which will trigger the flood heuristic, unshadowing the pagetables before the first userspace access. One particular guest, though (Xenner) will run the kernel in userspace, triggering the oops. Since the heuristic is incorrect in this case, we can simply remove it. Signed-off-by: Avi Kivity --- arch/x86/kvm/mmu.c | 6 ------ 1 file changed, 6 deletions(-) (limited to 'arch/x86/kvm/mmu.c') diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index baa6503894d..7e7c3969f7a 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -1083,10 +1083,6 @@ static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *shadow_pte, struct kvm_mmu_page *shadow; spte |= PT_WRITABLE_MASK; - if (user_fault) { - mmu_unshadow(vcpu->kvm, gfn); - goto unshadowed; - } shadow = kvm_mmu_lookup_page(vcpu->kvm, gfn); if (shadow || @@ -1103,8 +1099,6 @@ static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *shadow_pte, } } -unshadowed: - if (pte_access & ACC_WRITE_MASK) mark_page_dirty(vcpu->kvm, gfn); -- cgit v1.2.3