[PATCH 07/21] KVM: x86/mmu: Topup memory caches after walking GVA->GPA

From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Marc Zyngier <maz@kernel.org>, Paul Mackerras <paulus@ozlabs.org>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Janosch Frank <frankja@linux.ibm.com>,
	Paolo Bonzini <pbonzini@redhat.com>
Cc: Wanpeng Li <wanpengli@tencent.com>,
	kvm@vger.kernel.org, David Hildenbrand <david@redhat.com>,
	linux-mips@vger.kernel.org, Ben Gardon <bgardon@google.com>,
	Claudio Imbrenda <imbrenda@linux.ibm.com>,
	kvmarm@lists.cs.columbia.edu, Joerg Roedel <joro@8bytes.org>,
	Junaid Shahid <junaids@google.com>,
	kvm-ppc@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	Jim Mattson <jmattson@google.com>,
	Cornelia Huck <cohuck@redhat.com>,
	Peter Shier <pshier@google.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	linux-kernel@vger.kernel.org,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Peter Feiner <pfeiner@google.com>
Subject: [PATCH 07/21] KVM: x86/mmu: Topup memory caches after walking GVA->GPA
Date: Fri,  5 Jun 2020 14:38:39 -0700	[thread overview]
Message-ID: <20200605213853.14959-8-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20200605213853.14959-1-sean.j.christopherson@intel.com>

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 f5a1e9f89504f ("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.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/kvm/mmu/paging_tmpl.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index 38c576495048..3de32122f601 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -791,10 +791,6 @@ 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.
@@ -822,6 +818,10 @@ 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,
-- 
2.26.0

_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
