diff options
author | Avi Kivity <avi@qumranet.com> | 2007-12-30 13:29:05 +0300 |
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committer | Avi Kivity <avi@qumranet.com> | 2008-01-30 19:01:21 +0300 |
commit | d7824fff896a1698a07a8046dc362f4500c302f7 (patch) | |
tree | 249e23ec224bc621bea1ef24fa83f5a749d6b35b /arch/x86/kvm/mmu.c | |
parent | 7ec54588210df29ea637e6054489bc942c0ef371 (diff) | |
download | linux-d7824fff896a1698a07a8046dc362f4500c302f7.tar.xz |
KVM: MMU: Avoid calling gfn_to_page() in mmu_set_spte()
Since gfn_to_page() is a sleeping function, and we want to make the core mmu
spinlocked, we need to pass the page from the walker context (which can sleep)
to the shadow context (which cannot).
[marcelo: avoid recursive locking of mmap_sem]
Signed-off-by: Avi Kivity <avi@qumranet.com>
Diffstat (limited to 'arch/x86/kvm/mmu.c')
-rw-r--r-- | arch/x86/kvm/mmu.c | 55 |
1 files changed, 50 insertions, 5 deletions
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 3b91227969a5..c0b757be7b99 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -890,11 +890,10 @@ struct page *gva_to_page(struct kvm_vcpu *vcpu, gva_t gva) static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *shadow_pte, unsigned pt_access, unsigned pte_access, int user_fault, int write_fault, int dirty, - int *ptwrite, gfn_t gfn) + int *ptwrite, gfn_t gfn, struct page *page) { u64 spte; int was_rmapped = is_rmap_pte(*shadow_pte); - struct page *page; pgprintk("%s: spte %llx access %x write_fault %d" " user_fault %d gfn %lx\n", @@ -912,8 +911,6 @@ static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *shadow_pte, if (!(pte_access & ACC_EXEC_MASK)) spte |= PT64_NX_MASK; - page = gfn_to_page(vcpu->kvm, gfn); - spte |= PT_PRESENT_MASK; if (pte_access & ACC_USER_MASK) spte |= PT_USER_MASK; @@ -979,6 +976,11 @@ static int __nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn) int level = PT32E_ROOT_LEVEL; hpa_t table_addr = vcpu->arch.mmu.root_hpa; int pt_write = 0; + struct page *page; + + down_read(¤t->mm->mmap_sem); + page = gfn_to_page(vcpu->kvm, gfn); + up_read(¤t->mm->mmap_sem); for (; ; level--) { u32 index = PT64_INDEX(v, level); @@ -989,7 +991,7 @@ static int __nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn) if (level == 1) { mmu_set_spte(vcpu, &table[index], ACC_ALL, ACC_ALL, - 0, write, 1, &pt_write, gfn); + 0, write, 1, &pt_write, gfn, page); return pt_write || is_io_pte(table[index]); } @@ -1005,6 +1007,7 @@ static int __nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn) NULL); if (!new_table) { pgprintk("nonpaging_map: ENOMEM\n"); + kvm_release_page_clean(page); return -ENOMEM; } @@ -1347,6 +1350,43 @@ static bool last_updated_pte_accessed(struct kvm_vcpu *vcpu) return !!(spte && (*spte & PT_ACCESSED_MASK)); } +static void mmu_guess_page_from_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, + const u8 *new, int bytes) +{ + gfn_t gfn; + int r; + u64 gpte = 0; + + if (bytes != 4 && bytes != 8) + return; + + /* + * Assume that the pte write on a page table of the same type + * as the current vcpu paging mode. This is nearly always true + * (might be false while changing modes). Note it is verified later + * by update_pte(). + */ + if (is_pae(vcpu)) { + /* Handle a 32-bit guest writing two halves of a 64-bit gpte */ + if ((bytes == 4) && (gpa % 4 == 0)) { + r = kvm_read_guest(vcpu->kvm, gpa & ~(u64)7, &gpte, 8); + if (r) + return; + memcpy((void *)&gpte + (gpa % 8), new, 4); + } else if ((bytes == 8) && (gpa % 8 == 0)) { + memcpy((void *)&gpte, new, 8); + } + } else { + if ((bytes == 4) && (gpa % 4 == 0)) + memcpy((void *)&gpte, new, 4); + } + if (!is_present_pte(gpte)) + return; + gfn = (gpte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT; + vcpu->arch.update_pte.gfn = gfn; + vcpu->arch.update_pte.page = gfn_to_page(vcpu->kvm, gfn); +} + void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new, int bytes) { @@ -1367,6 +1407,7 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, int npte; pgprintk("%s: gpa %llx bytes %d\n", __FUNCTION__, gpa, bytes); + mmu_guess_page_from_pte_write(vcpu, gpa, new, bytes); mutex_lock(&vcpu->kvm->lock); ++vcpu->kvm->stat.mmu_pte_write; kvm_mmu_audit(vcpu, "pre pte write"); @@ -1437,6 +1478,10 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, } kvm_mmu_audit(vcpu, "post pte write"); mutex_unlock(&vcpu->kvm->lock); + if (vcpu->arch.update_pte.page) { + kvm_release_page_clean(vcpu->arch.update_pte.page); + vcpu->arch.update_pte.page = NULL; + } } int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva) |