[PATCH v5 2/6] KVM: SVM: Add helper to generate GHCB MSR verson info, and drop macro

Joerg Roedel
2021-10-20T12:44:37Z

From: Sean Christopherson <seanjc@google.com>

Convert the GHCB_MSR_SEV_INFO macro into a helper function, and have the
helper hardcode the min/max versions instead of relying on the caller to
do the same. Under no circumstance should different pieces of KVM define
different min/max versions.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/include/asm/sev-common.h | 5 -----
arch/x86/kvm/svm/sev.c | 24 ++++++++++++++++++------
arch/x86/kvm/svm/svm.h | 5 -----
3 files changed, 18 insertions(+), 16 deletions(-)

diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
index 8540972cad04..886c36f0cb16 100644
--- a/arch/x86/include/asm/sev-common.h
+++ b/arch/x86/include/asm/sev-common.h
@@ -24,11 +24,6 @@
#define GHCB_MSR_VER_MIN_MASK 0xffff
#define GHCB_MSR_CBIT_POS 24
#define GHCB_MSR_CBIT_MASK 0xff
-#define GHCB_MSR_SEV_INFO(_max, _min, _cbit) \
- ((((_max) & GHCB_MSR_VER_MAX_MASK) << GHCB_MSR_VER_MAX_POS) | \
- (((_min) & GHCB_MSR_VER_MIN_MASK) << GHCB_MSR_VER_MIN_POS) | \
- (((_cbit) & GHCB_MSR_CBIT_MASK) << GHCB_MSR_CBIT_POS) | \
- GHCB_MSR_SEV_INFO_RESP)
#define GHCB_MSR_INFO(v) ((v) & 0xfffUL)
#define GHCB_MSR_PROTO_MAX(v) (((v) >> GHCB_MSR_VER_MAX_POS) & GHCB_MSR_VER_MAX_MASK)
#define GHCB_MSR_PROTO_MIN(v) (((v) >> GHCB_MSR_VER_MIN_POS) & GHCB_MSR_VER_MIN_MASK)
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 2e3ecab6f1c8..9fb4d8fad1f4 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -2389,6 +2389,22 @@ static u64 ghcb_msr_cpuid_resp(u64 reg, u64 value)
return msr;
}

+/* The min/max GHCB version supported by KVM. */
+#define GHCB_VERSION_MAX 1ULL
+#define GHCB_VERSION_MIN 1ULL
+
+static u64 ghcb_msr_version_info(void)
+{
+ u64 msr;
+
+ msr = GHCB_MSR_SEV_INFO_RESP;
+ msr |= GHCB_VERSION_MAX << GHCB_MSR_VER_MAX_POS;
+ msr |= GHCB_VERSION_MIN << GHCB_MSR_VER_MIN_POS;
+ msr |= sev_enc_bit << GHCB_MSR_CBIT_POS;
+
+ return msr;
+}
+
static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm)
{
struct vmcb_control_area *control = &svm->vmcb->control;
@@ -2403,9 +2419,7 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm)

switch (ghcb_info) {
case GHCB_MSR_SEV_INFO_REQ:
- svm->vmcb->control.ghcb_gpa = GHCB_MSR_SEV_INFO(GHCB_VERSION_MAX,
- GHCB_VERSION_MIN,
- sev_enc_bit);
+ control->ghcb_gpa = ghcb_msr_version_info();
break;
case GHCB_MSR_CPUID_REQ: {
u64 cpuid_fn, cpuid_reg, cpuid_value;
@@ -2621,9 +2635,7 @@ void sev_es_vcpu_reset(struct vcpu_svm *svm)
* Set the GHCB MSR value as per the GHCB specification when emulating
* vCPU RESET for an SEV-ES guest.
*/
- svm->vmcb->control.ghcb_gpa = GHCB_MSR_SEV_INFO(GHCB_VERSION_MAX,
- GHCB_VERSION_MIN,
- sev_enc_bit);
+ svm->vmcb->control.ghcb_gpa = ghcb_msr_version_info();
}

void sev_es_prepare_guest_switch(struct vcpu_svm *svm, unsigned int cpu)
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 0d7bbe548ac3..68e5f16a0554 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -544,11 +544,6 @@ void svm_vcpu_blocking(struct kvm_vcpu *vcpu);
void svm_vcpu_unblocking(struct kvm_vcpu *vcpu);

/* sev.c */
-
-#define GHCB_VERSION_MAX 1ULL
-#define GHCB_VERSION_MIN 1ULL
-
-
extern unsigned int max_sev_asid;

void sev_vm_destroy(struct kvm *kvm);
--
2.33.1