Commit d4193132 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

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: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20221130230934.1014142-37-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 462689b3

arch/x86/include/asm/kvm_host.h

+0 −2
Original line number Diff line number Diff line
@@ -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);

arch/x86/kvm/svm/svm.c

+17 −21
Original line number Diff line number Diff line
@@ -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 @@ 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,
@@ -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;

arch/x86/kvm/vmx/vmx.c

+20 −17
Original line number Diff line number Diff line
@@ -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.

arch/x86/kvm/x86.c

+0 −11
Original line number Diff line number Diff line
@@ -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