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KVM: x86: disconnect kvm_check_cpuid() from vcpu->arch.cpuid_entries

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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@intel.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20201001130541.1398392-2-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Vitaly Kuznetsov 2020-10-01 15:05:39 +02:00 committed by Paolo Bonzini
parent 3ee6fb4949
commit f69858fcc7
1 changed files with 23 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

38
arch/x86/kvm/cpuid.c
View File

@ -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;
@ -227,7 +244,7 @@ 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);
@ -257,7 +274,7 @@ 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;
@ -947,17 +964,8 @@ out_free:
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);