[PATCH 12/21] KVM: x86/mmu: Skip filling the gfn cache for guaranteed direct MMU topups

Sean Christopherson
2020-06-05T21:39:21Z

Don't bother filling the gfn array cache when the caller is a fully
direct MMU, i.e. won't need a gfn array for shadow pages.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/kvm/mmu/mmu.c | 18 ++++++++++--------
arch/x86/kvm/mmu/paging_tmpl.h | 4 ++--
2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index a8f8eebf67df..8d66cf558f1b 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1101,7 +1101,7 @@ static void mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
}
}

-static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu)
+static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu, bool maybe_indirect)
{
int r;

@@ -1114,10 +1114,12 @@ static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu)
PT64_ROOT_MAX_LEVEL);
if (r)
return r;
- r = mmu_topup_memory_cache(&vcpu->arch.mmu_gfn_array_cache,
- PT64_ROOT_MAX_LEVEL);
- if (r)
- return r;
+ if (maybe_indirect) {
+ r = mmu_topup_memory_cache(&vcpu->arch.mmu_gfn_array_cache,
+ PT64_ROOT_MAX_LEVEL);
+ if (r)
+ return r;
+ }
return mmu_topup_memory_cache(&vcpu->arch.mmu_page_header_cache,
PT64_ROOT_MAX_LEVEL);
}
@@ -4107,7 +4109,7 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
if (fast_page_fault(vcpu, gpa, error_code))
return RET_PF_RETRY;

- r = mmu_topup_memory_caches(vcpu);
+ r = mmu_topup_memory_caches(vcpu, false);
if (r)
return r;

@@ -5147,7 +5149,7 @@ int kvm_mmu_load(struct kvm_vcpu *vcpu)
{
int r;

- r = mmu_topup_memory_caches(vcpu);
+ r = mmu_topup_memory_caches(vcpu, !vcpu->arch.mmu->direct_map);
if (r)
goto out;
r = mmu_alloc_roots(vcpu);
@@ -5341,7 +5343,7 @@ static void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
* or not since pte prefetch is skiped if it does not have
* enough objects in the cache.
*/
- mmu_topup_memory_caches(vcpu);
+ mmu_topup_memory_caches(vcpu, true);

spin_lock(&vcpu->kvm->mmu_lock);

diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index 3de32122f601..ac39710d0594 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -818,7 +818,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gpa_t addr, u32 error_code,
return RET_PF_EMULATE;
}

- r = mmu_topup_memory_caches(vcpu);
+ r = mmu_topup_memory_caches(vcpu, true);
if (r)
return r;

@@ -905,7 +905,7 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva, hpa_t root_hpa)
* No need to check return value here, rmap_can_add() can
* help us to skip pte prefetch later.
*/
- mmu_topup_memory_caches(vcpu);
+ mmu_topup_memory_caches(vcpu, true);

if (!VALID_PAGE(root_hpa)) {
WARN_ON(1);
--
2.26.0