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Message-ID: <YU4u3Kk1UTQWfWZ4@google.com>
Date: Fri, 24 Sep 2021 20:04:53 +0000
From: Sean Christopherson <seanjc@...gle.com>
To: Joerg Roedel <joro@...tes.org>
Cc: Paolo Bonzini <pbonzini@...hat.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Jim Mattson <jmattson@...gle.com>, x86@...nel.org,
Brijesh Singh <brijesh.singh@....com>,
Tom Lendacky <thomas.lendacky@....com>, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org, Joerg Roedel <jroedel@...e.de>
Subject: Re: [PATCH v3 1/4] KVM: SVM: Get rid of set_ghcb_msr() and
*ghcb_msr_bits() functions
On Mon, Sep 13, 2021, Joerg Roedel wrote:
> static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm)
> @@ -2377,16 +2371,14 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm)
>
> switch (ghcb_info) {
> case GHCB_MSR_SEV_INFO_REQ:
> - set_ghcb_msr(svm, GHCB_MSR_SEV_INFO(GHCB_VERSION_MAX,
> - GHCB_VERSION_MIN,
> - sev_enc_bit));
> + svm->vmcb->control.ghcb_gpa = GHCB_MSR_SEV_INFO(GHCB_VERSION_MAX,
> + GHCB_VERSION_MIN,
> + sev_enc_bit);
Nit, "svm->vmcb->control." can be "control->".
With that fixed,
Reviewed-by: Sean Christopherson <seanjc@...gle.com>
> break;
> case GHCB_MSR_CPUID_REQ: {
> u64 cpuid_fn, cpuid_reg, cpuid_value;
>
> - cpuid_fn = get_ghcb_msr_bits(svm,
> - GHCB_MSR_CPUID_FUNC_MASK,
> - GHCB_MSR_CPUID_FUNC_POS);
> + cpuid_fn = GHCB_MSR_CPUID_FN(control->ghcb_gpa);
>
> /* Initialize the registers needed by the CPUID intercept */
> vcpu->arch.regs[VCPU_REGS_RAX] = cpuid_fn;
> @@ -2398,9 +2390,8 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm)
> break;
> }
>
> - cpuid_reg = get_ghcb_msr_bits(svm,
> - GHCB_MSR_CPUID_REG_MASK,
> - GHCB_MSR_CPUID_REG_POS);
> + cpuid_reg = GHCB_MSR_CPUID_REG(control->ghcb_gpa);
> +
> if (cpuid_reg == 0)
> cpuid_value = vcpu->arch.regs[VCPU_REGS_RAX];
> else if (cpuid_reg == 1)
> @@ -2410,26 +2401,19 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm)
> else
> cpuid_value = vcpu->arch.regs[VCPU_REGS_RDX];
>
> - set_ghcb_msr_bits(svm, cpuid_value,
> - GHCB_MSR_CPUID_VALUE_MASK,
> - GHCB_MSR_CPUID_VALUE_POS);
> + svm->vmcb->control.ghcb_gpa = ghcb_msr_cpuid_resp(cpuid_reg, cpuid_value);
>
> - set_ghcb_msr_bits(svm, GHCB_MSR_CPUID_RESP,
> - GHCB_MSR_INFO_MASK,
> - GHCB_MSR_INFO_POS);
I don't mind using a helper instead of a macro (I completely agree the helper is
easier to read), but we should be consistent, i.e. get rid of GHCB_MSR_SEV_INFO.
And IMO that helper should handle the min/max version, not the callers. Add this
after patch 01 (modulo the above nit)?
>From 5c329f9e7156948697955a2745f32df024aa5ee6 Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@...gle.com>
Date: Fri, 24 Sep 2021 12:58:31 -0700
Subject: [PATCH] KVM: SVM: Add helper to generate GHCB MSR verson info, and
drop macro
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@...gle.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 7aa6ad4c3118..159b22bb74e4 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);
--
2.33.0.685.g46640cef36-goog
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