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KVM: x86: Introduce kvm_check_cpuid()

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Use kvm_check_cpuid() to validate if userspace provides legal cpuid
settings and call it before KVM take any action to update CPUID or
update vcpu states based on given CPUID settings.

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <20200709043426.92712-2-xiaoyao.li@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Xiaoyao Li 2020-07-09 12:34:22 +08:00 committed by Paolo Bonzini
parent 36f37648ca
commit a76733a987
2 changed files with 36 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

55
arch/x86/kvm/cpuid.c
View File

@ -54,7 +54,26 @@ static u32 xstate_required_size(u64 xstate_bv, bool compacted)
#define F feature_bit #define F feature_bit
int kvm_update_cpuid(struct kvm_vcpu *vcpu) static int kvm_check_cpuid(struct kvm_vcpu *vcpu)
{
struct kvm_cpuid_entry2 *best;
/*
* 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);
if (best) {
int vaddr_bits = (best->eax & 0xff00) >> 8;
if (vaddr_bits != 48 && vaddr_bits != 57 && vaddr_bits != 0)
return -EINVAL;
}
return 0;
}
void kvm_update_cpuid(struct kvm_vcpu *vcpu)
{ {
struct kvm_cpuid_entry2 *best; struct kvm_cpuid_entry2 *best;
struct kvm_lapic *apic = vcpu->arch.apic; struct kvm_lapic *apic = vcpu->arch.apic;
@ -98,18 +117,6 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu)
cpuid_entry_has(best, X86_FEATURE_XSAVEC))) cpuid_entry_has(best, X86_FEATURE_XSAVEC)))
best->ebx = xstate_required_size(vcpu->arch.xcr0, true); best->ebx = xstate_required_size(vcpu->arch.xcr0, true);
/*
* 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);
if (best) {
int vaddr_bits = (best->eax & 0xff00) >> 8;
if (vaddr_bits != 48 && vaddr_bits != 57 && vaddr_bits != 0)
return -EINVAL;
}
best = kvm_find_cpuid_entry(vcpu, KVM_CPUID_FEATURES, 0); best = kvm_find_cpuid_entry(vcpu, KVM_CPUID_FEATURES, 0);
if (kvm_hlt_in_guest(vcpu->kvm) && best && if (kvm_hlt_in_guest(vcpu->kvm) && best &&
(best->eax & (1 << KVM_FEATURE_PV_UNHALT))) (best->eax & (1 << KVM_FEATURE_PV_UNHALT)))
@ -131,7 +138,6 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu)
kvm_pmu_refresh(vcpu); kvm_pmu_refresh(vcpu);
vcpu->arch.cr4_guest_rsvd_bits = vcpu->arch.cr4_guest_rsvd_bits =
__cr4_reserved_bits(guest_cpuid_has, vcpu); __cr4_reserved_bits(guest_cpuid_has, vcpu);
return 0;
} }
static int is_efer_nx(void) static int is_efer_nx(void)
@ -206,11 +212,16 @@ int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
vcpu->arch.cpuid_entries[i].padding[2] = 0; vcpu->arch.cpuid_entries[i].padding[2] = 0;
} }
vcpu->arch.cpuid_nent = cpuid->nent; vcpu->arch.cpuid_nent = cpuid->nent;
r = kvm_check_cpuid(vcpu);
if (r) {
vcpu->arch.cpuid_nent = 0;
kvfree(cpuid_entries);
goto out;
}
cpuid_fix_nx_cap(vcpu); cpuid_fix_nx_cap(vcpu);
kvm_x86_ops.cpuid_update(vcpu); kvm_x86_ops.cpuid_update(vcpu);
r = kvm_update_cpuid(vcpu); kvm_update_cpuid(vcpu);
if (r)
vcpu->arch.cpuid_nent = 0;
kvfree(cpuid_entries); kvfree(cpuid_entries);
out: out:
@ -231,10 +242,14 @@ int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu,
cpuid->nent * sizeof(struct kvm_cpuid_entry2))) cpuid->nent * sizeof(struct kvm_cpuid_entry2)))
goto out; goto out;
vcpu->arch.cpuid_nent = cpuid->nent; vcpu->arch.cpuid_nent = cpuid->nent;
kvm_x86_ops.cpuid_update(vcpu); r = kvm_check_cpuid(vcpu);
r = kvm_update_cpuid(vcpu); if (r) {
if (r)
vcpu->arch.cpuid_nent = 0; vcpu->arch.cpuid_nent = 0;
goto out;
}
kvm_x86_ops.cpuid_update(vcpu);
kvm_update_cpuid(vcpu);
out: out:
return r; return r;
} }

2
arch/x86/kvm/cpuid.h
View File

@ -9,7 +9,7 @@
extern u32 kvm_cpu_caps[NCAPINTS] __read_mostly; extern u32 kvm_cpu_caps[NCAPINTS] __read_mostly;
void kvm_set_cpu_caps(void); void kvm_set_cpu_caps(void);
int kvm_update_cpuid(struct kvm_vcpu *vcpu); void kvm_update_cpuid(struct kvm_vcpu *vcpu);
struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu,
u32 function, u32 index); u32 function, u32 index);
int kvm_dev_ioctl_get_cpuid(struct kvm_cpuid2 *cpuid, int kvm_dev_ioctl_get_cpuid(struct kvm_cpuid2 *cpuid,