[PATCH v2 2/3] KVM: x86: Move gpa_val and gpa_available into the emulator context

From: Sean Christopherson
Date: Tue Feb 18 2020 - 18:03:16 EST


Move the GPA tracking into the emulator context now that the context is
guaranteed to be initialized via __init_emulate_ctxt() prior to
dereferencing gpa_{available,val}, i.e. now that seeing a stale
gpa_available will also trigger a WARN due to an invalid context.

Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
---
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 03946eb3e2b9..a4ef19a6e612 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -311,6 +311,10 @@ 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 10c1e8f472b6..9c79c41eb5f6 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -798,10 +798,6 @@ 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 92af6c5a69e3..f88b72932c35 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5736,10 +5736,9 @@ 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);
@@ -6408,6 +6407,7 @@ 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;

@@ -6838,8 +6838,8 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,

/* 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_or_gpa;
+ ctxt->gpa_available = true;
+ ctxt->gpa_val = cr2_or_gpa;
}
} else {
/* Sanitize the address out of an abundance of paranoia. */
@@ -8443,7 +8443,6 @@ 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, exit_fastpath);
return r;

--
2.24.1