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KVM: MMU: fast prefetch spte on invlpg path

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Fast prefetch spte for the unsync shadow page on invlpg path

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Xiao Guangrong 2011-09-22 16:56:39 +08:00 committed by Avi Kivity
parent 505aef8f30
commit f57f2ef58f
4 changed files with 36 additions and 40 deletions
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4
arch/x86/include/asm/kvm_host.h
View File

@ -461,7 +461,6 @@ struct kvm_arch {
unsigned int n_requested_mmu_pages;
unsigned int n_max_mmu_pages;
unsigned int indirect_shadow_pages;
atomic_t invlpg_counter;
struct hlist_head mmu_page_hash[KVM_NUM_MMU_PAGES];
/*
* Hash table of struct kvm_mmu_page.
@ -757,8 +756,7 @@ int fx_init(struct kvm_vcpu *vcpu);
void kvm_mmu_flush_tlb(struct kvm_vcpu *vcpu);
void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
const u8 *new, int bytes,
bool guest_initiated);
const u8 *new, int bytes);
int kvm_mmu_unprotect_page(struct kvm *kvm, gfn_t gfn);
int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva);
void __kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu);

16
arch/x86/kvm/mmu.c
View File

@ -3531,8 +3531,7 @@ static bool last_updated_pte_accessed(struct kvm_vcpu *vcpu)
}
void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
const u8 *new, int bytes,
bool guest_initiated)
const u8 *new, int bytes)
{
gfn_t gfn = gpa >> PAGE_SHIFT;
union kvm_mmu_page_role mask = { .word = 0 };
@ -3541,7 +3540,7 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
LIST_HEAD(invalid_list);
u64 entry, gentry, *spte;
unsigned pte_size, page_offset, misaligned, quadrant, offset;
int level, npte, invlpg_counter, r, flooded = 0;
int level, npte, r, flooded = 0;
bool remote_flush, local_flush, zap_page;
/*
@ -3556,19 +3555,16 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
pgprintk("%s: gpa %llx bytes %d\n", __func__, gpa, bytes);
invlpg_counter = atomic_read(&vcpu->kvm->arch.invlpg_counter);
/*
* Assume that the pte write on a page table of the same type
* as the current vcpu paging mode since we update the sptes only
* when they have the same mode.
*/
if ((is_pae(vcpu) && bytes == 4) || !new) {
if (is_pae(vcpu) && bytes == 4) {
/* Handle a 32-bit guest writing two halves of a 64-bit gpte */
if (is_pae(vcpu)) {
gpa &= ~(gpa_t)7;
bytes = 8;
}
r = kvm_read_guest(vcpu->kvm, gpa, &gentry, min(bytes, 8));
if (r)
gentry = 0;
@ -3594,12 +3590,9 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
*/
mmu_topup_memory_caches(vcpu);
spin_lock(&vcpu->kvm->mmu_lock);
if (atomic_read(&vcpu->kvm->arch.invlpg_counter) != invlpg_counter)
gentry = 0;
kvm_mmu_free_some_pages(vcpu);
++vcpu->kvm->stat.mmu_pte_write;
trace_kvm_mmu_audit(vcpu, AUDIT_PRE_PTE_WRITE);
if (guest_initiated) {
if (gfn == vcpu->arch.last_pt_write_gfn
&& !last_updated_pte_accessed(vcpu)) {
++vcpu->arch.last_pt_write_count;
@ -3610,7 +3603,6 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
vcpu->arch.last_pt_write_count = 1;
vcpu->arch.last_pte_updated = NULL;
}
}
mask.cr0_wp = mask.cr4_pae = mask.nxe = 1;
for_each_gfn_indirect_valid_sp(vcpu->kvm, sp, gfn, node) {

30
arch/x86/kvm/paging_tmpl.h
View File

@ -672,20 +672,27 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva)
{
struct kvm_shadow_walk_iterator iterator;
struct kvm_mmu_page *sp;
gpa_t pte_gpa = -1;
int level;
u64 *sptep;
vcpu_clear_mmio_info(vcpu, gva);
spin_lock(&vcpu->kvm->mmu_lock);
/*
* No need to check return value here, rmap_can_add() can
* help us to skip pte prefetch later.
*/
mmu_topup_memory_caches(vcpu);
spin_lock(&vcpu->kvm->mmu_lock);
for_each_shadow_entry(vcpu, gva, iterator) {
level = iterator.level;
sptep = iterator.sptep;
sp = page_header(__pa(sptep));
if (is_last_spte(*sptep, level)) {
pt_element_t gpte;
gpa_t pte_gpa;
if (!sp->unsync)
break;
@ -694,22 +701,21 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva)
if (mmu_page_zap_pte(vcpu->kvm, sp, sptep))
kvm_flush_remote_tlbs(vcpu->kvm);
if (!rmap_can_add(vcpu))
break;
if (kvm_read_guest_atomic(vcpu->kvm, pte_gpa, &gpte,
sizeof(pt_element_t)))
break;
FNAME(update_pte)(vcpu, sp, sptep, &gpte);
}
if (!is_shadow_present_pte(*sptep) || !sp->unsync_children)
break;
}
atomic_inc(&vcpu->kvm->arch.invlpg_counter);
spin_unlock(&vcpu->kvm->mmu_lock);
if (pte_gpa == -1)
return;
if (mmu_topup_memory_caches(vcpu))
return;
kvm_mmu_pte_write(vcpu, pte_gpa, NULL, sizeof(pt_element_t), 0);
}
static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr, u32 access,

4
arch/x86/kvm/x86.c
View File

@ -4087,7 +4087,7 @@ int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa,
ret = kvm_write_guest(vcpu->kvm, gpa, val, bytes);
if (ret < 0)
return 0;
kvm_mmu_pte_write(vcpu, gpa, val, bytes, 1);
kvm_mmu_pte_write(vcpu, gpa, val, bytes);
return 1;
}
@ -4324,7 +4324,7 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt,
if (!exchanged)
return X86EMUL_CMPXCHG_FAILED;
kvm_mmu_pte_write(vcpu, gpa, new, bytes, 1);
kvm_mmu_pte_write(vcpu, gpa, new, bytes);
return X86EMUL_CONTINUE;