[PATCH v2 36/50] KVM: x86: Do VMX/SVM support checks directly in vendor code
Sean Christopherson
seanjc at google.com
Wed Nov 30 15:09:20 PST 2022
Do basic VMX/SVM support checks directly in vendor code instead of
implementing them via kvm_x86_ops hooks. Beyond the superficial benefit
of providing common messages, which isn't even clearly a net positive
since vendor code can provide more precise/detailed messages, there's
zero advantage to bouncing through common x86 code.
Consolidating the checks will also simplify performing the checks
across all CPUs (in a future patch).
Signed-off-by: Sean Christopherson <seanjc at google.com>
---
arch/x86/include/asm/kvm_host.h | 2 --
arch/x86/kvm/svm/svm.c | 38 +++++++++++++++------------------
arch/x86/kvm/vmx/vmx.c | 37 +++++++++++++++++---------------
arch/x86/kvm/x86.c | 11 ----------
4 files changed, 37 insertions(+), 51 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 04a9ae66fb8d..d79aedf70908 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1729,8 +1729,6 @@ struct kvm_x86_nested_ops {
};
struct kvm_x86_init_ops {
- int (*cpu_has_kvm_support)(void);
- int (*disabled_by_bios)(void);
int (*check_processor_compatibility)(void);
int (*hardware_setup)(void);
unsigned int (*handle_intel_pt_intr)(void);
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index ab53da3fbcd1..49ccef9fae81 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -519,21 +519,28 @@ static void svm_init_osvw(struct kvm_vcpu *vcpu)
vcpu->arch.osvw.status |= 1;
}
-static int has_svm(void)
+static bool kvm_is_svm_supported(void)
{
const char *msg;
+ u64 vm_cr;
if (!cpu_has_svm(&msg)) {
- printk(KERN_INFO "has_svm: %s\n", msg);
- return 0;
+ pr_err("SVM not supported, %s\n", msg);
+ return false;
}
if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT)) {
pr_info("KVM is unsupported when running as an SEV guest\n");
- return 0;
+ return false;
}
- return 1;
+ rdmsrl(MSR_VM_CR, vm_cr);
+ if (vm_cr & (1 << SVM_VM_CR_SVM_DISABLE)) {
+ pr_err("SVM disabled (by BIOS) in MSR_VM_CR\n");
+ return false;
+ }
+
+ return true;
}
void __svm_write_tsc_multiplier(u64 multiplier)
@@ -572,10 +579,9 @@ static int svm_hardware_enable(void)
if (efer & EFER_SVME)
return -EBUSY;
- if (!has_svm()) {
- pr_err("%s: err EOPNOTSUPP on %d\n", __func__, me);
+ if (!kvm_is_svm_supported())
return -EINVAL;
- }
+
sd = per_cpu_ptr(&svm_data, me);
sd->asid_generation = 1;
sd->max_asid = cpuid_ebx(SVM_CPUID_FUNC) - 1;
@@ -4070,17 +4076,6 @@ static void svm_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa,
vmcb_mark_dirty(svm->vmcb, VMCB_CR);
}
-static int is_disabled(void)
-{
- u64 vm_cr;
-
- rdmsrl(MSR_VM_CR, vm_cr);
- if (vm_cr & (1 << SVM_VM_CR_SVM_DISABLE))
- return 1;
-
- return 0;
-}
-
static void
svm_patch_hypercall(struct kvm_vcpu *vcpu, unsigned char *hypercall)
{
@@ -5080,8 +5075,6 @@ static __init int svm_hardware_setup(void)
static struct kvm_x86_init_ops svm_init_ops __initdata = {
- .cpu_has_kvm_support = has_svm,
- .disabled_by_bios = is_disabled,
.hardware_setup = svm_hardware_setup,
.check_processor_compatibility = svm_check_processor_compat,
@@ -5095,6 +5088,9 @@ static int __init svm_init(void)
__unused_size_checks();
+ if (!kvm_is_svm_supported())
+ return -EOPNOTSUPP;
+
r = kvm_x86_vendor_init(&svm_init_ops);
if (r)
return r;
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 3f7d9f88b314..23b64bf4bfcf 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2485,17 +2485,6 @@ static void vmx_cache_reg(struct kvm_vcpu *vcpu, enum kvm_reg reg)
}
}
-static __init int cpu_has_kvm_support(void)
-{
- return cpu_has_vmx();
-}
-
-static __init int vmx_disabled_by_bios(void)
-{
- return !this_cpu_has(X86_FEATURE_MSR_IA32_FEAT_CTL) ||
- !this_cpu_has(X86_FEATURE_VMX);
-}
-
static int kvm_cpu_vmxon(u64 vmxon_pointer)
{
u64 msr;
@@ -7479,16 +7468,29 @@ static int vmx_vm_init(struct kvm *kvm)
return 0;
}
+static bool __init kvm_is_vmx_supported(void)
+{
+ if (!cpu_has_vmx()) {
+ pr_err("CPU doesn't support VMX\n");
+ return false;
+ }
+
+ if (!this_cpu_has(X86_FEATURE_MSR_IA32_FEAT_CTL) ||
+ !this_cpu_has(X86_FEATURE_VMX)) {
+ pr_err("VMX not enabled (by BIOS) in MSR_IA32_FEAT_CTL\n");
+ return false;
+ }
+
+ return true;
+}
+
static int __init vmx_check_processor_compat(void)
{
struct vmcs_config vmcs_conf;
struct vmx_capability vmx_cap;
- if (!this_cpu_has(X86_FEATURE_MSR_IA32_FEAT_CTL) ||
- !this_cpu_has(X86_FEATURE_VMX)) {
- pr_err("VMX is disabled on CPU %d\n", smp_processor_id());
+ if (!kvm_is_vmx_supported())
return -EIO;
- }
if (setup_vmcs_config(&vmcs_conf, &vmx_cap) < 0)
return -EIO;
@@ -8499,8 +8501,6 @@ static __init int hardware_setup(void)
}
static struct kvm_x86_init_ops vmx_init_ops __initdata = {
- .cpu_has_kvm_support = cpu_has_kvm_support,
- .disabled_by_bios = vmx_disabled_by_bios,
.check_processor_compatibility = vmx_check_processor_compat,
.hardware_setup = hardware_setup,
.handle_intel_pt_intr = NULL,
@@ -8543,6 +8543,9 @@ static int __init vmx_init(void)
{
int r, cpu;
+ if (!kvm_is_vmx_supported())
+ return -EOPNOTSUPP;
+
/*
* Note, hv_init_evmcs() touches only VMX knobs, i.e. there's nothing
* to unwind if a later step fails.
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 3d5455e08191..5551f3552f08 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9315,17 +9315,6 @@ static int __kvm_x86_vendor_init(struct kvm_x86_init_ops *ops)
return -EEXIST;
}
- if (!ops->cpu_has_kvm_support()) {
- pr_err_ratelimited("no hardware support for '%s'\n",
- ops->runtime_ops->name);
- return -EOPNOTSUPP;
- }
- if (ops->disabled_by_bios()) {
- pr_err_ratelimited("support for '%s' disabled by bios\n",
- ops->runtime_ops->name);
- return -EOPNOTSUPP;
- }
-
/*
* KVM explicitly assumes that the guest has an FPU and
* FXSAVE/FXRSTOR. For example, the KVM_GET_FPU explicitly casts the
--
2.38.1.584.g0f3c55d4c2-goog
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