[PATCH v2 03/66] KVM: x86: Simplify handling of Centaur CPUID leafs

Sean Christopherson
2020-03-03T00:02:48Z

Refactor the handling of the Centaur-only CPUID leaf to detect the leaf
via a runtime query instead of adding a one-off callback in the static
array. When the callback was introduced, there were additional fields
in the array's structs, and more importantly, retpoline wasn't a thing.

No functional change intended.

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/kvm/cpuid.c | 32 ++++++++++----------------------
1 file changed, 10 insertions(+), 22 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index f49fdd06f511..de52cbb46171 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -829,15 +829,7 @@ static int do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 func,
return __do_cpuid_func(entry, func, nent, maxnent);
}

-struct kvm_cpuid_param {
- u32 func;
- bool (*qualifier)(const struct kvm_cpuid_param *param);
-};
-
-static bool is_centaur_cpu(const struct kvm_cpuid_param *param)
-{
- return boot_cpu_data.x86_vendor == X86_VENDOR_CENTAUR;
-}
+#define CENTAUR_CPUID_SIGNATURE 0xC0000000

static int get_cpuid_func(struct kvm_cpuid_entry2 *entries, u32 func,
int *nent, int maxnent, unsigned int type)
@@ -845,6 +837,10 @@ static int get_cpuid_func(struct kvm_cpuid_entry2 *entries, u32 func,
u32 limit;
int r;

+ if (func == CENTAUR_CPUID_SIGNATURE &&
+ boot_cpu_data.x86_vendor != X86_VENDOR_CENTAUR)
+ return 0;
+
r = do_cpuid_func(&entries[*nent], func, nent, maxnent, type);
if (r)
return r;
@@ -896,11 +892,8 @@ int kvm_dev_ioctl_get_cpuid(struct kvm_cpuid2 *cpuid,
struct kvm_cpuid_entry2 *cpuid_entries;
int nent = 0, r = -E2BIG, i;

- static const struct kvm_cpuid_param param[] = {
- { .func = 0 },
- { .func = 0x80000000 },
- { .func = 0xC0000000, .qualifier = is_centaur_cpu },
- { .func = KVM_CPUID_SIGNATURE },
+ static const u32 funcs[] = {
+ 0, 0x80000000, CENTAUR_CPUID_SIGNATURE, KVM_CPUID_SIGNATURE,
};

if (cpuid->nent < 1)
@@ -918,14 +911,9 @@ int kvm_dev_ioctl_get_cpuid(struct kvm_cpuid2 *cpuid,
goto out;

r = 0;
- for (i = 0; i < ARRAY_SIZE(param); i++) {
- const struct kvm_cpuid_param *ent = &param[i];
-
- if (ent->qualifier && !ent->qualifier(ent))
- continue;
-
- r = get_cpuid_func(cpuid_entries, ent->func, &nent,
- cpuid->nent, type);
+ for (i = 0; i < ARRAY_SIZE(funcs); i++) {
+ r = get_cpuid_func(cpuid_entries, funcs[i], &nent, cpuid->nent,
+ type);
if (r)
goto out_free;
}
--
2.24.1