KVM: x86: Do VMX/SVM support checks directly in vendor code

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@google.com>
Message-Id: <20221130230934.1014142-37-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 4899505955b57f58a790ee0910154b071c7e886c..f20a3005468862d23697e3829e6c71c891f8d388 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1722,8 +1722,6 @@ 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 f7192a14fc8995f0901346d0900d6fcbabd88646..177ee63c8197a1e2d08ffa3dab37ab67c11cdc0f 100644 (file)
--- 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;
@@ -4076,17 +4082,6 @@ 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)
 {
@@ -5086,8 +5081,6 @@ err:
 
 
 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,
 
@@ -5101,6 +5094,9 @@ 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 a3c681336a396a0b777f52de04eb37bc5e091cf6..08b1b70924290f17d272c503f3d1b33c43dc5437 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2516,17 +2516,6 @@ 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;
@@ -7522,16 +7511,29 @@ 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;
@@ -8542,8 +8544,6 @@ 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,
@@ -8586,6 +8586,9 @@ 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 4c40bbec372ab0cd73166ee1cc313c9b8e9267e2..cad48a80697f14f309a4db72be88e619a0e60ecd 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9330,17 +9330,6 @@ 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