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Subject[PATCH 29/44] KVM: x86: Do CPU compatibility checks in x86 code
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Move the CPU compatibility checks to pure x86 code, i.e. drop x86's use
of the common kvm_x86_check_cpu_compat() arch hook. x86 is the only
architecture that "needs" to do per-CPU compatibility checks, moving
the logic to x86 will allow dropping the common code, and will also
give x86 more control over when/how the compatibility checks are
performed, e.g. TDX will need to enable hardware (do VMXON) in order to
perform compatibility checks.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/svm/svm.c | 2 +-
arch/x86/kvm/vmx/vmx.c | 2 +-
arch/x86/kvm/x86.c | 49 ++++++++++++++++++++++++++++++++----------
3 files changed, 40 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index f48d07bfc3d7..368b4db4b240 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -5144,7 +5144,7 @@ static int __init svm_init(void)
* Common KVM initialization _must_ come last, after this, /dev/kvm is
* exposed to userspace!
*/
- r = kvm_init(&svm_init_ops, sizeof(struct vcpu_svm),
+ r = kvm_init(NULL, sizeof(struct vcpu_svm),
__alignof__(struct vcpu_svm), THIS_MODULE);
if (r)
goto err_kvm_init;
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 81690fce0eb1..26baaccb659a 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -8562,7 +8562,7 @@ static int __init vmx_init(void)
* Common KVM initialization _must_ come last, after this, /dev/kvm is
* exposed to userspace!
*/
- r = kvm_init(&vmx_init_ops, sizeof(struct vcpu_vmx),
+ r = kvm_init(NULL, sizeof(struct vcpu_vmx),
__alignof__(struct vcpu_vmx), THIS_MODULE);
if (r)
goto err_kvm_init;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2b4530a33298..94831f1a1d04 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9271,10 +9271,36 @@ static inline void kvm_ops_update(struct kvm_x86_init_ops *ops)
kvm_pmu_ops_update(ops->pmu_ops);
}

+struct kvm_cpu_compat_check {
+ struct kvm_x86_init_ops *ops;
+ int *ret;
+};
+
+static int kvm_x86_check_processor_compatibility(struct kvm_x86_init_ops *ops)
+{
+ struct cpuinfo_x86 *c = &cpu_data(smp_processor_id());
+
+ WARN_ON(!irqs_disabled());
+
+ if (__cr4_reserved_bits(cpu_has, c) !=
+ __cr4_reserved_bits(cpu_has, &boot_cpu_data))
+ return -EIO;
+
+ return ops->check_processor_compatibility();
+}
+
+static void kvm_x86_check_cpu_compat(void *data)
+{
+ struct kvm_cpu_compat_check *c = data;
+
+ *c->ret = kvm_x86_check_processor_compatibility(c->ops);
+}
+
static int __kvm_x86_vendor_init(struct kvm_x86_init_ops *ops)
{
+ struct kvm_cpu_compat_check c;
u64 host_pat;
- int r;
+ int r, cpu;

if (kvm_x86_ops.hardware_enable) {
pr_err("kvm: already loaded vendor module '%s'\n", kvm_x86_ops.name);
@@ -9354,6 +9380,14 @@ static int __kvm_x86_vendor_init(struct kvm_x86_init_ops *ops)
if (r != 0)
goto out_mmu_exit;

+ c.ret = &r;
+ c.ops = ops;
+ for_each_online_cpu(cpu) {
+ smp_call_function_single(cpu, kvm_x86_check_cpu_compat, &c, 1);
+ if (r < 0)
+ goto out_hardware_unsetup;
+ }
+
/*
* Point of no return! DO NOT add error paths below this point unless
* absolutely necessary, as most operations from this point forward
@@ -9396,6 +9430,8 @@ static int __kvm_x86_vendor_init(struct kvm_x86_init_ops *ops)
kvm_init_msr_list();
return 0;

+out_hardware_unsetup:
+ ops->runtime_ops->hardware_unsetup();
out_mmu_exit:
kvm_mmu_vendor_module_exit();
out_free_percpu:
@@ -12002,16 +12038,7 @@ void kvm_arch_hardware_disable(void)

int kvm_arch_check_processor_compat(void *opaque)
{
- struct cpuinfo_x86 *c = &cpu_data(smp_processor_id());
- struct kvm_x86_init_ops *ops = opaque;
-
- WARN_ON(!irqs_disabled());
-
- if (__cr4_reserved_bits(cpu_has, c) !=
- __cr4_reserved_bits(cpu_has, &boot_cpu_data))
- return -EIO;
-
- return ops->check_processor_compatibility();
+ return 0;
}

bool kvm_vcpu_is_reset_bsp(struct kvm_vcpu *vcpu)
--
2.38.1.431.g37b22c650d-goog
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