linux-kernel - [PATCH 2/3] KVM: x86: Move gpa_val and gpa

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Message-Id: <20191122225832.26684-3-sean.j.christopherson@intel.com>
Date:   Fri, 22 Nov 2019 14:58:31 -0800
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/3] KVM: x86: Move gpa_val and gpa_available into the emulator context

Move the GPA tracking into the emulator context to prevent it from being
abused in the standard page fault flow.  All paths into the emulator go
through init_emulate_ctxt(), so there's no need to clear gpa_available
after every VM-Exit.  The only partial exception is EMULTYPE_NO_DECODE,
but in that case the emulator is simply being re-entered, i.e. retaining
gpa_available is correct and consistent with current behavior.

Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/include/asm/kvm_emulate.h |  4 ++++
 arch/x86/include/asm/kvm_host.h    |  4 ----
 arch/x86/kvm/x86.c                 | 13 ++++++-------
 3 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index 77cf6c11f66b..e81658a4ab9d 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -307,6 +307,10 @@ struct x86_emulate_ctxt {
 	bool have_exception;
 	struct x86_exception exception;
 
+	/* GPA available */
+	bool gpa_available;
+	gpa_t gpa_val;
+
 	/*
 	 * decode cache
 	 */
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 6311fffbc2f0..e434f4cfecd1 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -791,10 +791,6 @@ struct kvm_vcpu_arch {
 	int pending_ioapic_eoi;
 	int pending_external_vector;
 
-	/* GPA available */
-	bool gpa_available;
-	gpa_t gpa_val;
-
 	/* be preempted when it's in kernel-mode(cpl=0) */
 	bool preempted_in_kernel;
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 848e4ec21c5e..9a8adfdf1e0a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5664,10 +5664,9 @@ static int emulator_read_write_onepage(unsigned long addr, void *val,
 	 * operation using rep will only have the initial GPA from the NPF
 	 * occurred.
 	 */
-	if (vcpu->arch.gpa_available &&
-	    emulator_can_use_gpa(ctxt) &&
-	    (addr & ~PAGE_MASK) == (vcpu->arch.gpa_val & ~PAGE_MASK)) {
-		gpa = vcpu->arch.gpa_val;
+	if (ctxt->gpa_available && emulator_can_use_gpa(ctxt) &&
+	    (addr & ~PAGE_MASK) == (ctxt->gpa_val & ~PAGE_MASK)) {
+		gpa = ctxt->gpa_val;
 		ret = vcpu_is_mmio_gpa(vcpu, addr, gpa, write);
 	} else {
 		ret = vcpu_mmio_gva_to_gpa(vcpu, addr, &gpa, exception, write);
@@ -6318,6 +6317,7 @@ static void init_emulate_ctxt(struct kvm_vcpu *vcpu)
 
 	kvm_x86_ops->get_cs_db_l_bits(vcpu, &cs_db, &cs_l);
 
+	ctxt->gpa_available = false;
 	ctxt->eflags = kvm_get_rflags(vcpu);
 	ctxt->tf = (ctxt->eflags & X86_EFLAGS_TF) != 0;
 
@@ -6750,8 +6750,8 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu,
 
 		/* With shadow page tables, cr2 contains a GVA or nGPA. */
 		if (vcpu->arch.mmu->direct_map) {
-			vcpu->arch.gpa_available = true;
-			vcpu->arch.gpa_val = cr2;
+			ctxt->gpa_available = true;
+			ctxt->gpa_val = cr2;
 		}
 	} else {
 		/* Sanitize the address out of an abundance of paranoia. */
@@ -8306,7 +8306,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 	if (vcpu->arch.apic_attention)
 		kvm_lapic_sync_from_vapic(vcpu);
 
-	vcpu->arch.gpa_available = false;
 	r = kvm_x86_ops->handle_exit(vcpu);
 	return r;
 
-- 
2.24.0