Commit f3747a5a authored Jul 02, 2020 by Sean Christopherson Committed by Paolo Bonzini Jul 09, 2020

KVM: x86/mmu: Topup memory caches after walking GVA->GPA



Topup memory caches after walking the GVA->GPA translation during a
shadow page fault, there is no need to ensure the caches are full when
walking the GVA.  As of commit f5a1e9f8 ("KVM: MMU: remove call
to kvm_mmu_pte_write from walk_addr"), the FNAME(walk_addr) flow no
longer add rmaps via kvm_mmu_pte_write().

This avoids allocating memory in the case that the GVA is unmapped in
the guest, and also provides a paper trail of why/when the memory caches
need to be filled.

Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200703023545.8771-8-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

parent 83291445

arch/x86/kvm/mmu/paging_tmpl.h

+4 −4

Original line number	Diff line number	Diff line
		@@ -789,10 +789,6 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gpa_t addr, u32 error_code,

		pgprintk("%s: addr %lx err %x\n", __func__, addr, error_code);

		r = mmu_topup_memory_caches(vcpu);
		if (r)
		return r;

		/*
		* If PFEC.RSVD is set, this is a shadow page fault.
		* The bit needs to be cleared before walking guest page tables.
		@@ -820,6 +816,10 @@ 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);
		if (r)
		return r;

		vcpu->arch.write_fault_to_shadow_pgtable = false;

		is_self_change_mapping = FNAME(is_self_change_mapping)(vcpu,

Admin message