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KVM: x86/mmu: Add common helper to handle prefetching SPTEs

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Deduplicate the prefetching code for indirect and direct MMUs.  The core
logic is the same, the only difference is that indirect MMUs need to
prefetch SPTEs one-at-a-time, as contiguous guest virtual addresses aren't
guaranteed to yield contiguous guest physical addresses.

Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-40-seanjc@google.com>
This commit is contained in:
Sean Christopherson
2024-10-10 11:23:41 -07:00
committed by Paolo Bonzini
parent 64d5cd99f7
commit fa8fe58d1e
2 changed files with 26 additions and 27 deletions
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40
arch/x86/kvm/mmu/mmu.c
View File

@@ -2950,32 +2950,41 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot,
return ret;
}
static int direct_pte_prefetch_many(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *sp,
u64 *start, u64 *end)
static bool kvm_mmu_prefetch_sptes(struct kvm_vcpu *vcpu, gfn_t gfn, u64 *sptep,
int nr_pages, unsigned int access)
{
struct page *pages[PTE_PREFETCH_NUM];
struct kvm_memory_slot *slot;
unsigned int access = sp->role.access;
int i, ret;
gfn_t gfn;
int i;
if (WARN_ON_ONCE(nr_pages > PTE_PREFETCH_NUM))
return false;
gfn = kvm_mmu_page_get_gfn(sp, spte_index(start));
slot = gfn_to_memslot_dirty_bitmap(vcpu, gfn, access & ACC_WRITE_MASK);
if (!slot)
return -1;
return false;
ret = kvm_prefetch_pages(slot, gfn, pages, end - start);
if (ret <= 0)
return -1;
nr_pages = kvm_prefetch_pages(slot, gfn, pages, nr_pages);
if (nr_pages <= 0)
return false;
for (i = 0; i < ret; i++, gfn++, start++) {
mmu_set_spte(vcpu, slot, start, access, gfn,
for (i = 0; i < nr_pages; i++, gfn++, sptep++) {
mmu_set_spte(vcpu, slot, sptep, access, gfn,
page_to_pfn(pages[i]), NULL);
kvm_release_page_clean(pages[i]);
}
return 0;
return true;
}
static bool direct_pte_prefetch_many(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *sp,
u64 *start, u64 *end)
{
gfn_t gfn = kvm_mmu_page_get_gfn(sp, spte_index(start));
unsigned int access = sp->role.access;
return kvm_mmu_prefetch_sptes(vcpu, gfn, start, end - start, access);
}
static void __direct_pte_prefetch(struct kvm_vcpu *vcpu,
@@ -2993,8 +3002,9 @@ static void __direct_pte_prefetch(struct kvm_vcpu *vcpu,
if (is_shadow_present_pte(*spte) || spte == sptep) {
if (!start)
continue;
if (direct_pte_prefetch_many(vcpu, sp, start, spte) < 0)
if (!direct_pte_prefetch_many(vcpu, sp, start, spte))
return;
start = NULL;
} else if (!start)
start = spte;

13
arch/x86/kvm/mmu/paging_tmpl.h
View File

@@ -533,9 +533,7 @@ static bool
FNAME(prefetch_gpte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
u64 *spte, pt_element_t gpte)
{
struct kvm_memory_slot *slot;
unsigned pte_access;
struct page *page;
gfn_t gfn;
if (FNAME(prefetch_invalid_gpte)(vcpu, sp, spte, gpte))
@@ -545,16 +543,7 @@ FNAME(prefetch_gpte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
pte_access = sp->role.access & FNAME(gpte_access)(gpte);
FNAME(protect_clean_gpte)(vcpu->arch.mmu, &pte_access, gpte);
slot = gfn_to_memslot_dirty_bitmap(vcpu, gfn, pte_access & ACC_WRITE_MASK);
if (!slot)
return false;
if (kvm_prefetch_pages(slot, gfn, &page, 1) != 1)
return false;
mmu_set_spte(vcpu, slot, spte, pte_access, gfn, page_to_pfn(page), NULL);
kvm_release_page_clean(page);
return true;
return kvm_mmu_prefetch_sptes(vcpu, gfn, spte, 1, pte_access);
}
static bool FNAME(gpte_changed)(struct kvm_vcpu *vcpu,