[PATCH 3/3] KVM: SVM: Move RESET emulation to svm_vcpu_reset()

Sean Christopherson
2021-09-14T23:09:37Z

Move RESET emulation for SVM vCPUs to svm_vcpu_reset(), and drop an extra
init_vmcb() from svm_create_vcpu() in the process. Hopefully KVM will
someday expose a dedicated RESET ioctl(), and in the meantime separating
"create" from "RESET" is a nice cleanup.

Keep the call to svm_switch_vmcb() so that misuse of svm->vmcb at worst
breaks the guest, e.g. premature accesses doesn't cause a NULL pointer
dereference.

Cc: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/svm/sev.c | 6 +++---
arch/x86/kvm/svm/svm.c | 29 +++++++++++++++++------------
arch/x86/kvm/svm/svm.h | 2 +-
3 files changed, 21 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 75e0b21ad07c..4cf40021dde4 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -2599,11 +2599,11 @@ void sev_es_init_vmcb(struct vcpu_svm *svm)
set_msr_interception(vcpu, svm->msrpm, MSR_IA32_LASTINTTOIP, 1, 1);
}

-void sev_es_create_vcpu(struct vcpu_svm *svm)
+void sev_es_vcpu_reset(struct vcpu_svm *svm)
{
/*
- * Set the GHCB MSR value as per the GHCB specification when creating
- * a vCPU for an SEV-ES guest.
+ * Set the GHCB MSR value as per the GHCB specification when emulating
+ * vCPU RESET for an SEV-ES guest.
*/
set_ghcb_msr(svm, GHCB_MSR_SEV_INFO(GHCB_VERSION_MAX,
GHCB_VERSION_MIN,
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 1a70e11f0487..bb79ae8e8bcd 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1303,6 +1303,19 @@ static void init_vmcb(struct kvm_vcpu *vcpu)

}

+static void __svm_vcpu_reset(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_svm *svm = to_svm(vcpu);
+
+ svm_vcpu_init_msrpm(vcpu, svm->msrpm);
+
+ svm_init_osvw(vcpu);
+ vcpu->arch.microcode_version = 0x01000065;
+
+ if (sev_es_guest(vcpu->kvm))
+ sev_es_vcpu_reset(svm);
+}
+
static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
{
struct vcpu_svm *svm = to_svm(vcpu);
@@ -1311,6 +1324,9 @@ static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
svm->virt_spec_ctrl = 0;

init_vmcb(vcpu);
+
+ if (!init_event)
+ __svm_vcpu_reset(vcpu);
}

void svm_switch_vmcb(struct vcpu_svm *svm, struct kvm_vmcb_info *target_vmcb)
@@ -1370,24 +1386,13 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu)

svm->vmcb01.ptr = page_address(vmcb01_page);
svm->vmcb01.pa = __sme_set(page_to_pfn(vmcb01_page) << PAGE_SHIFT);
+ svm_switch_vmcb(svm, &svm->vmcb01);

if (vmsa_page)
svm->vmsa = page_address(vmsa_page);

svm->guest_state_loaded = false;

- svm_switch_vmcb(svm, &svm->vmcb01);
- init_vmcb(vcpu);
-
- svm_vcpu_init_msrpm(vcpu, svm->msrpm);
-
- svm_init_osvw(vcpu);
- vcpu->arch.microcode_version = 0x01000065;
-
- if (sev_es_guest(vcpu->kvm))
- /* Perform SEV-ES specific VMCB creation updates */
- sev_es_create_vcpu(svm);
-
return 0;

error_free_vmsa_page:
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 524d943f3efc..001698919148 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -561,7 +561,7 @@ void sev_free_vcpu(struct kvm_vcpu *vcpu);
int sev_handle_vmgexit(struct kvm_vcpu *vcpu);
int sev_es_string_io(struct vcpu_svm *svm, int size, unsigned int port, int in);
void sev_es_init_vmcb(struct vcpu_svm *svm);
-void sev_es_create_vcpu(struct vcpu_svm *svm);
+void sev_es_vcpu_reset(struct vcpu_svm *svm);
void sev_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, u8 vector);
void sev_es_prepare_guest_switch(struct vcpu_svm *svm, unsigned int cpu);
void sev_es_unmap_ghcb(struct vcpu_svm *svm);
--
2.33.0.309.g3052b89438-goog