[PATCH 10/21] KVM: x86/mmu: Make __GFP_ZERO a property of the memory cache

Sean Christopherson
2020-06-05T21:43:49Z

Add a gfp_zero flag to 'struct kvm_mmu_memory_cache' and use it to
control __GFP_ZERO instead of hardcoding a call to kmem_cache_zalloc().
A future patch needs such a flag for the __get_free_page() path, as
gfn arrays do not need/want the allocator to zero the memory. Convert
the kmem_cache paths to __GFP_ZERO now so as to avoid a weird and
inconsistent API in the future.

No functional change intended.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/mmu/mmu.c | 7 ++++++-
2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index e7a427547557..fb99e6776e27 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -251,6 +251,7 @@ struct kvm_kernel_irq_routing_entry;
*/
struct kvm_mmu_memory_cache {
int nobjs;
+ gfp_t gfp_zero;
struct kmem_cache *kmem_cache;
void *objects[KVM_NR_MEM_OBJS];
};
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index d245acece3cd..6b0ec9060786 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1063,8 +1063,10 @@ static void walk_shadow_page_lockless_end(struct kvm_vcpu *vcpu)
static inline void *mmu_memory_cache_alloc_obj(struct kvm_mmu_memory_cache *mc,
gfp_t gfp_flags)
{
+ gfp_flags |= mc->gfp_zero;
+
if (mc->kmem_cache)
- return kmem_cache_zalloc(mc->kmem_cache, gfp_flags);
+ return kmem_cache_alloc(mc->kmem_cache, gfp_flags);
else
return (void *)__get_free_page(gfp_flags);
}
@@ -5680,7 +5682,10 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu)
int ret;

vcpu->arch.mmu_pte_list_desc_cache.kmem_cache = pte_list_desc_cache;
+ vcpu->arch.mmu_pte_list_desc_cache.gfp_zero = __GFP_ZERO;
+
vcpu->arch.mmu_page_header_cache.kmem_cache = mmu_page_header_cache;
+ vcpu->arch.mmu_page_header_cache.gfp_zero = __GFP_ZERO;

vcpu->arch.mmu = &vcpu->arch.root_mmu;
vcpu->arch.walk_mmu = &vcpu->arch.root_mmu;
--
2.26.0