As a preparatory step to allocating vcpu->arch.cpuid_entries dynamically
make kvm_check_cpuid() check work with an arbitrary 'struct kvm_cpuid_entry2'
array.
Currently, when kvm_check_cpuid() fails we reset vcpu->arch.cpuid_nent to
0 and this is kind of weird, i.e. one would expect CPUIDs to remain
unchanged when KVM_SET_CPUID[2] call fails.
No functional change intended. It would've been possible to move the updated
kvm_check_cpuid() in kvm_vcpu_ioctl_set_cpuid2() and check the supplied
input before we start updating vcpu->arch.cpuid_entries/nent but we
can't do the same in kvm_vcpu_ioctl_set_cpuid() as we'll have to copy
'struct kvm_cpuid_entry' entries first. The change will be made when
vcpu->arch.cpuid_entries[] array becomes allocated dynamically.
Suggested-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
arch/x86/kvm/cpuid.c | 38 +++++++++++++++++++++++---------------
1 file changed, 23 insertions(+), 15 deletions(-)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 37c3668a774f..529348ddedc1 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -54,7 +54,24 @@ static u32 xstate_required_size(u64 xstate_bv, bool compacted)
#define F feature_bit
-static int kvm_check_cpuid(struct kvm_vcpu *vcpu)
+static inline struct kvm_cpuid_entry2 *cpuid_entry2_find(
+ struct kvm_cpuid_entry2 *entries, int nent, u32 function, u32 index)
+{
+ struct kvm_cpuid_entry2 *e;
+ int i;
+
+ for (i = 0; i < nent; i++) {
+ e = &entries[i];
+
+ if (e->function == function && (e->index == index ||
+ !(e->flags & KVM_CPUID_FLAG_SIGNIFCANT_INDEX)))
+ return e;
+ }
+
+ return NULL;
+}
+
+static int kvm_check_cpuid(struct kvm_cpuid_entry2 *entries, int nent)
{
struct kvm_cpuid_entry2 *best;
@@ -62,7 +79,7 @@ static int kvm_check_cpuid(struct kvm_vcpu *vcpu)
* The existing code assumes virtual address is 48-bit or 57-bit in the
* canonical address checks; exit if it is ever changed.
*/
- best = kvm_find_cpuid_entry(vcpu, 0x80000008, 0);
+ best = cpuid_entry2_find(entries, nent, 0x80000008, 0);
if (best) {
int vaddr_bits = (best->eax & 0xff00) >> 8;
@@ -220,7 +237,7 @@ int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
vcpu->arch.cpuid_entries[i].padding[2] = 0;
}
vcpu->arch.cpuid_nent = cpuid->nent;
- r = kvm_check_cpuid(vcpu);
+ r = kvm_check_cpuid(vcpu->arch.cpuid_entries, cpuid->nent);
if (r) {
vcpu->arch.cpuid_nent = 0;
kvfree(cpuid_entries);
@@ -250,7 +267,7 @@ int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu,
cpuid->nent * sizeof(struct kvm_cpuid_entry2)))
goto out;
vcpu->arch.cpuid_nent = cpuid->nent;
- r = kvm_check_cpuid(vcpu);
+ r = kvm_check_cpuid(vcpu->arch.cpuid_entries, cpuid->nent);
if (r) {
vcpu->arch.cpuid_nent = 0;
goto out;
@@ -940,17 +957,8 @@ int kvm_dev_ioctl_get_cpuid(struct kvm_cpuid2 *cpuid,
struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu,
u32 function, u32 index)
{
- struct kvm_cpuid_entry2 *e;
- int i;
-
- for (i = 0; i < vcpu->arch.cpuid_nent; ++i) {
- e = &vcpu->arch.cpuid_entries[i];
-
- if (e->function == function && (e->index == index ||
- !(e->flags & KVM_CPUID_FLAG_SIGNIFCANT_INDEX)))
- return e;
- }
- return NULL;
+ return cpuid_entry2_find(vcpu->arch.cpuid_entries, vcpu->arch.cpuid_nent,
+ function, index);
}
EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry);
--
2.25.4
