Using bit 1 (PTE_LIST_WP_BIT) in rmap store the write-protect status to avoid unnecessary shadow page walking
Signed-off-by: Xiao Guangrong <[email protected]> --- arch/x86/kvm/mmu.c | 40 ++++++++++++++++++++++++++++++++++------ 1 files changed, 34 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 0c6e92d..8b71908 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -796,7 +796,9 @@ static int mapping_level(struct kvm_vcpu *vcpu, gfn_t large_gfn) return level - 1; } -#define PTE_LIST_DESC (0x1ull) +#define PTE_LIST_DESC_BIT 0 +#define PTE_LIST_WP_BIT 1 +#define PTE_LIST_DESC (1 << PTE_LIST_DESC_BIT) #define PTE_LIST_FLAG_MASK (0x3ull) static void @@ -1067,6 +1069,12 @@ static bool rmap_can_add(struct kvm_vcpu *vcpu) return mmu_memory_cache_free_objects(cache); } +static void host_page_write_protect(u64 *spte, unsigned long *rmapp) +{ + if (!(*spte & SPTE_HOST_WRITEABLE)) + __test_and_set_bit(PTE_LIST_WP_BIT, rmapp); +} + static int rmap_add(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn) { struct kvm_mmu_page *sp; @@ -1074,7 +1082,10 @@ static int rmap_add(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn) sp = page_header(__pa(spte)); kvm_mmu_page_set_gfn(sp, spte - sp->spt, gfn); + rmapp = gfn_to_rmap(vcpu->kvm, gfn, sp->role.level); + host_page_write_protect(spte, rmapp); + return pte_list_add(vcpu, spte, rmapp); } @@ -1164,16 +1175,23 @@ static bool rmap_write_protect(struct kvm *kvm, u64 gfn) { struct kvm_memory_slot *slot; unsigned long *rmapp; - int i; + int i = PT_PAGE_TABLE_LEVEL; bool write_protected = false; slot = gfn_to_memslot(kvm, gfn); + rmapp = __gfn_to_rmap(gfn, i, slot); + + if (__test_and_set_bit(PTE_LIST_WP_BIT, rmapp)) + return false; + + do { + write_protected |= __rmap_write_protect(kvm, rmapp, i++); + + if (i >= PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES) + break; - for (i = PT_PAGE_TABLE_LEVEL; - i < PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES; ++i) { rmapp = __gfn_to_rmap(gfn, i, slot); - write_protected |= __rmap_write_protect(kvm, rmapp, i); - } + } while (true); return write_protected; } @@ -1225,6 +1243,7 @@ static int kvm_set_pte_rmapp(struct kvm *kvm, unsigned long *rmapp, mmu_spte_clear_track_bits(sptep); mmu_spte_set(sptep, new_spte); + host_page_write_protect(sptep, rmapp); } } @@ -2291,9 +2310,15 @@ static int mmu_need_write_protect(struct kvm_vcpu *vcpu, gfn_t gfn, { struct kvm_mmu_page *s; struct hlist_node *node; + unsigned long *rmap; bool need_unsync = false; + rmap = gfn_to_rmap(vcpu->kvm, gfn, PT_PAGE_TABLE_LEVEL); + if (!vcpu->kvm->arch.indirect_shadow_pages) + goto write_free; + + if (!test_bit(PTE_LIST_WP_BIT, rmap)) return 0; for_each_gfn_indirect_valid_sp(vcpu->kvm, s, gfn, node) { @@ -2309,6 +2334,9 @@ static int mmu_need_write_protect(struct kvm_vcpu *vcpu, gfn_t gfn, } if (need_unsync) kvm_unsync_pages(vcpu, gfn); + +write_free: + __clear_bit(PTE_LIST_WP_BIT, rmap); return 0; } -- 1.7.7.6 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
