A sunsequent patch will need to acquire the CPUID leaf range for emulated
Xen so explicitly pass the signature of the hypervisor we're interested in
to the new function. Also introduce a new kvm_hypervisor_cpuid structure
so we can neatly store both the base and limit leaf indices.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
---
Cc: Sean Christopherson <seanjc@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
v6:
- New in this version
---
arch/x86/include/asm/kvm_host.h | 7 ++++++-
arch/x86/kvm/cpuid.c | 15 ++++++++-------
2 files changed, 14 insertions(+), 8 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index f35f1ff4427b..ff201ad35551 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -710,6 +710,11 @@ struct kvm_queued_exception {
bool has_payload;
};
+struct kvm_hypervisor_cpuid {
+ u32 base;
+ u32 limit;
+};
+
struct kvm_vcpu_arch {
/*
* rip and regs accesses must go through
@@ -826,7 +831,7 @@ struct kvm_vcpu_arch {
int cpuid_nent;
struct kvm_cpuid_entry2 *cpuid_entries;
- u32 kvm_cpuid_base;
+ struct kvm_hypervisor_cpuid kvm_cpuid;
u64 reserved_gpa_bits;
int maxphyaddr;
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 0b5bf013fcb8..2468720f8d84 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -180,12 +180,13 @@ static int kvm_cpuid_check_equal(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2
return 0;
}
-static void kvm_update_kvm_cpuid_base(struct kvm_vcpu *vcpu)
+static void kvm_update_hypervisor_cpuid(struct kvm_vcpu *vcpu, const char *hypervisor_signature,
+ struct kvm_hypervisor_cpuid *hypervisor_cpuid)
{
u32 function;
struct kvm_cpuid_entry2 *entry;
- vcpu->arch.kvm_cpuid_base = 0;
+ memset(hypervisor_cpuid, 0, sizeof(*hypervisor_cpuid));
for_each_possible_hypervisor_cpuid_base(function) {
entry = kvm_find_cpuid_entry(vcpu, function);
@@ -197,9 +198,9 @@ static void kvm_update_kvm_cpuid_base(struct kvm_vcpu *vcpu)
signature[1] = entry->ecx;
signature[2] = entry->edx;
- BUILD_BUG_ON(sizeof(signature) > sizeof(KVM_SIGNATURE));
- if (!memcmp(signature, KVM_SIGNATURE, sizeof(signature))) {
- vcpu->arch.kvm_cpuid_base = function;
+ if (!memcmp(signature, hypervisor_signature, sizeof(signature))) {
+ hypervisor_cpuid->base = function;
+ hypervisor_cpuid->limit = entry->eax;
break;
}
}
@@ -209,7 +210,7 @@ static void kvm_update_kvm_cpuid_base(struct kvm_vcpu *vcpu)
static struct kvm_cpuid_entry2 *__kvm_find_kvm_cpuid_features(struct kvm_vcpu *vcpu,
struct kvm_cpuid_entry2 *entries, int nent)
{
- u32 base = vcpu->arch.kvm_cpuid_base;
+ u32 base = vcpu->arch.kvm_cpuid.base;
if (!base)
return NULL;
@@ -439,7 +440,7 @@ static int kvm_set_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2,
vcpu->arch.cpuid_entries = e2;
vcpu->arch.cpuid_nent = nent;
- kvm_update_kvm_cpuid_base(vcpu);
+ kvm_update_hypervisor_cpuid(vcpu, KVM_SIGNATURE, &vcpu->arch.kvm_cpuid);
kvm_vcpu_after_set_cpuid(vcpu);
return 0;
--
2.20.1On Tue, Dec 20, 2022, Paul Durrant wrote:
> A sunsequent patch will need to acquire the CPUID leaf range for emulated
> Xen so explicitly pass the signature of the hypervisor we're interested in
> to the new function. Also introduce a new kvm_hypervisor_cpuid structure
> so we can neatly store both the base and limit leaf indices.
>
> Signed-off-by: Paul Durrant <pdurrant@amazon.com>
> ---
> Cc: Sean Christopherson <seanjc@google.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: Dave Hansen <dave.hansen@linux.intel.com>
> Cc: David Woodhouse <dwmw2@infradead.org>
>
> v6:
> - New in this version
> ---
> arch/x86/include/asm/kvm_host.h | 7 ++++++-
> arch/x86/kvm/cpuid.c | 15 ++++++++-------
> 2 files changed, 14 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index f35f1ff4427b..ff201ad35551 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -710,6 +710,11 @@ struct kvm_queued_exception {
> bool has_payload;
> };
>
> +struct kvm_hypervisor_cpuid {
> + u32 base;
> + u32 limit;
> +};
Probably makes sense to place this above "struct kvm_vcpu_xen" right away to
avoid the (very minor) churn.
> struct kvm_vcpu_arch {
> /*
> * rip and regs accesses must go through
> @@ -826,7 +831,7 @@ struct kvm_vcpu_arch {
>
> int cpuid_nent;
> struct kvm_cpuid_entry2 *cpuid_entries;
> - u32 kvm_cpuid_base;
> + struct kvm_hypervisor_cpuid kvm_cpuid;
>
> u64 reserved_gpa_bits;
> int maxphyaddr;
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 0b5bf013fcb8..2468720f8d84 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -180,12 +180,13 @@ static int kvm_cpuid_check_equal(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2
> return 0;
> }
>
> -static void kvm_update_kvm_cpuid_base(struct kvm_vcpu *vcpu)
> +static void kvm_update_hypervisor_cpuid(struct kvm_vcpu *vcpu, const char *hypervisor_signature,
Please wrap. The 80 char limit is a soft limit, but should still be honored unless
there's a good reason to run over.
I also vote to name the param "sig" to keep line lengths short.
> + struct kvm_hypervisor_cpuid *hypervisor_cpuid)
Since the struct is a 64-bit value, what about making this a pure getter that
returns a copy?
static struct kvm_hypervisor_cpuid kvm_get_hypervisor_cpuid(struct kvm_vcpu *vcpu,
const char *sig)
{
struct kvm_hypervisor_cpuid cpuid = {};
struct kvm_cpuid_entry2 *entry;
u32 function;
for_each_possible_hypervisor_cpuid_base(cpuid.base) {
entry = kvm_find_cpuid_entry(vcpu, function);
if (entry) {
u32 signature[3];
signature[0] = entry->ebx;
signature[1] = entry->ecx;
signature[2] = entry->edx;
if (!memcmp(signature, sig, sizeof(signature))) {
cpuid.base = function;
cpuid.limit = entry->eax;
break;
}
}
}
return cpuid;
}
vcpu->arch.kvm_cpuid = kvm_get_hypervisor_cpuid(vcpu, KVM_SIGNATURE);
vcpu->arch.xen.cpuid = kvm_get_hypervisor_cpuid(vcpu, XEN_SIGNATURE);
On 04/01/2023 19:34, Sean Christopherson wrote:
> On Tue, Dec 20, 2022, Paul Durrant wrote:
>> A sunsequent patch will need to acquire the CPUID leaf range for emulated
>> Xen so explicitly pass the signature of the hypervisor we're interested in
>> to the new function. Also introduce a new kvm_hypervisor_cpuid structure
>> so we can neatly store both the base and limit leaf indices.
>>
>> Signed-off-by: Paul Durrant <pdurrant@amazon.com>
>> ---
>> Cc: Sean Christopherson <seanjc@google.com>
>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>> Cc: Thomas Gleixner <tglx@linutronix.de>
>> Cc: Ingo Molnar <mingo@redhat.com>
>> Cc: Borislav Petkov <bp@alien8.de>
>> Cc: Dave Hansen <dave.hansen@linux.intel.com>
>> Cc: David Woodhouse <dwmw2@infradead.org>
>>
>> v6:
>> - New in this version
>> ---
>> arch/x86/include/asm/kvm_host.h | 7 ++++++-
>> arch/x86/kvm/cpuid.c | 15 ++++++++-------
>> 2 files changed, 14 insertions(+), 8 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
>> index f35f1ff4427b..ff201ad35551 100644
>> --- a/arch/x86/include/asm/kvm_host.h
>> +++ b/arch/x86/include/asm/kvm_host.h
>> @@ -710,6 +710,11 @@ struct kvm_queued_exception {
>> bool has_payload;
>> };
>>
>> +struct kvm_hypervisor_cpuid {
>> + u32 base;
>> + u32 limit;
>> +};
>
> Probably makes sense to place this above "struct kvm_vcpu_xen" right away to
> avoid the (very minor) churn.
>
Sure.
>> struct kvm_vcpu_arch {
>> /*
>> * rip and regs accesses must go through
>> @@ -826,7 +831,7 @@ struct kvm_vcpu_arch {
>>
>> int cpuid_nent;
>> struct kvm_cpuid_entry2 *cpuid_entries;
>> - u32 kvm_cpuid_base;
>> + struct kvm_hypervisor_cpuid kvm_cpuid;
>>
>> u64 reserved_gpa_bits;
>> int maxphyaddr;
>> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
>> index 0b5bf013fcb8..2468720f8d84 100644
>> --- a/arch/x86/kvm/cpuid.c
>> +++ b/arch/x86/kvm/cpuid.c
>> @@ -180,12 +180,13 @@ static int kvm_cpuid_check_equal(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2
>> return 0;
>> }
>>
>> -static void kvm_update_kvm_cpuid_base(struct kvm_vcpu *vcpu)
>> +static void kvm_update_hypervisor_cpuid(struct kvm_vcpu *vcpu, const char *hypervisor_signature,
>
> Please wrap. The 80 char limit is a soft limit, but should still be honored unless
> there's a good reason to run over.
Ok.
>
> I also vote to name the param "sig" to keep line lengths short.
>
>> + struct kvm_hypervisor_cpuid *hypervisor_cpuid)
>
> Since the struct is a 64-bit value, what about making this a pure getter that
> returns a copy?
>
> static struct kvm_hypervisor_cpuid kvm_get_hypervisor_cpuid(struct kvm_vcpu *vcpu,
> const char *sig)
> {
> struct kvm_hypervisor_cpuid cpuid = {};
> struct kvm_cpuid_entry2 *entry;
> u32 function;
>
> for_each_possible_hypervisor_cpuid_base(cpuid.base) {
> entry = kvm_find_cpuid_entry(vcpu, function);
>
> if (entry) {
> u32 signature[3];
>
> signature[0] = entry->ebx;
> signature[1] = entry->ecx;
> signature[2] = entry->edx;
>
> if (!memcmp(signature, sig, sizeof(signature))) {
> cpuid.base = function;
> cpuid.limit = entry->eax;
> break;
> }
> }
> }
>
> return cpuid;
> }
>
>
> vcpu->arch.kvm_cpuid = kvm_get_hypervisor_cpuid(vcpu, KVM_SIGNATURE);
> vcpu->arch.xen.cpuid = kvm_get_hypervisor_cpuid(vcpu, XEN_SIGNATURE);
Yes, if that's preferable then no problem.
Paul
On Thu, Jan 05, 2023, Paul Durrant wrote:
> On 04/01/2023 19:34, Sean Christopherson wrote:
> > Since the struct is a 64-bit value, what about making this a pure getter that
> > returns a copy?
> >
> > static struct kvm_hypervisor_cpuid kvm_get_hypervisor_cpuid(struct kvm_vcpu *vcpu,
> > const char *sig)
> > {
> > struct kvm_hypervisor_cpuid cpuid = {};
> > struct kvm_cpuid_entry2 *entry;
> > u32 function;
> >
> > for_each_possible_hypervisor_cpuid_base(cpuid.base) {
> > entry = kvm_find_cpuid_entry(vcpu, function);
> >
> > if (entry) {
> > u32 signature[3];
> >
> > signature[0] = entry->ebx;
> > signature[1] = entry->ecx;
> > signature[2] = entry->edx;
> >
> > if (!memcmp(signature, sig, sizeof(signature))) {
> > cpuid.base = function;
> > cpuid.limit = entry->eax;
> > break;
> > }
> > }
> > }
> >
> > return cpuid;
> > }
> >
> >
> > vcpu->arch.kvm_cpuid = kvm_get_hypervisor_cpuid(vcpu, KVM_SIGNATURE);
> > vcpu->arch.xen.cpuid = kvm_get_hypervisor_cpuid(vcpu, XEN_SIGNATURE);
>
> Yes, if that's preferable then no problem.
I like it (obviously), but it's probably worth waiting a few days to see what
others think before posting a new version.
On 05/01/2023 18:09, Sean Christopherson wrote:
> On Thu, Jan 05, 2023, Paul Durrant wrote:
>> On 04/01/2023 19:34, Sean Christopherson wrote:
>>> Since the struct is a 64-bit value, what about making this a pure getter that
>>> returns a copy?
>>>
>>> static struct kvm_hypervisor_cpuid kvm_get_hypervisor_cpuid(struct kvm_vcpu *vcpu,
>>> const char *sig)
>>> {
>>> struct kvm_hypervisor_cpuid cpuid = {};
>>> struct kvm_cpuid_entry2 *entry;
>>> u32 function;
>>>
>>> for_each_possible_hypervisor_cpuid_base(cpuid.base) {
>>> entry = kvm_find_cpuid_entry(vcpu, function);
>>>
>>> if (entry) {
>>> u32 signature[3];
>>>
>>> signature[0] = entry->ebx;
>>> signature[1] = entry->ecx;
>>> signature[2] = entry->edx;
>>>
>>> if (!memcmp(signature, sig, sizeof(signature))) {
>>> cpuid.base = function;
>>> cpuid.limit = entry->eax;
>>> break;
>>> }
>>> }
>>> }
>>>
>>> return cpuid;
>>> }
>>>
>>>
>>> vcpu->arch.kvm_cpuid = kvm_get_hypervisor_cpuid(vcpu, KVM_SIGNATURE);
>>> vcpu->arch.xen.cpuid = kvm_get_hypervisor_cpuid(vcpu, XEN_SIGNATURE);
>>
>> Yes, if that's preferable then no problem.
>
> I like it (obviously), but it's probably worth waiting a few days to see what
> others think before posting a new version.
I think it's cleaner too, and I already did the typing so I may as well
post. I don't think anyone else has expressed any strong opinions on the
code either way.
Paul
On Tue, 2022-12-20 at 13:40 +0000, Paul Durrant wrote:
> A sunsequent patch will need to acquire the CPUID leaf range for emulated
> Xen so explicitly pass the signature of the hypervisor we're interested in
> to the new function. Also introduce a new kvm_hypervisor_cpuid structure
> so we can neatly store both the base and limit leaf indices.
>
> Signed-off-by: Paul Durrant <pdurrant@amazon.com>
> ---
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
> Cc: Sean Christopherson <seanjc@google.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: Dave Hansen <dave.hansen@linux.intel.com>
> Cc: David Woodhouse <dwmw2@infradead.org>
>
> v6:
> - New in this version
> ---
> arch/x86/include/asm/kvm_host.h | 7 ++++++-
> arch/x86/kvm/cpuid.c | 15 ++++++++-------
> 2 files changed, 14 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index f35f1ff4427b..ff201ad35551 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -710,6 +710,11 @@ struct kvm_queued_exception {
> bool has_payload;
> };
>
> +struct kvm_hypervisor_cpuid {
> + u32 base;
> + u32 limit;
> +};
> +
> struct kvm_vcpu_arch {
> /*
> * rip and regs accesses must go through
> @@ -826,7 +831,7 @@ struct kvm_vcpu_arch {
>
> int cpuid_nent;
> struct kvm_cpuid_entry2 *cpuid_entries;
> - u32 kvm_cpuid_base;
> + struct kvm_hypervisor_cpuid kvm_cpuid;
>
> u64 reserved_gpa_bits;
> int maxphyaddr;
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 0b5bf013fcb8..2468720f8d84 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -180,12 +180,13 @@ static int kvm_cpuid_check_equal(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2
> return 0;
> }
>
> -static void kvm_update_kvm_cpuid_base(struct kvm_vcpu *vcpu)
> +static void kvm_update_hypervisor_cpuid(struct kvm_vcpu *vcpu, const char *hypervisor_signature,
> + struct kvm_hypervisor_cpuid *hypervisor_cpuid)
> {
> u32 function;
> struct kvm_cpuid_entry2 *entry;
>
> - vcpu->arch.kvm_cpuid_base = 0;
> + memset(hypervisor_cpuid, 0, sizeof(*hypervisor_cpuid));
>
> for_each_possible_hypervisor_cpuid_base(function) {
> entry = kvm_find_cpuid_entry(vcpu, function);
> @@ -197,9 +198,9 @@ static void kvm_update_kvm_cpuid_base(struct kvm_vcpu *vcpu)
> signature[1] = entry->ecx;
> signature[2] = entry->edx;
>
> - BUILD_BUG_ON(sizeof(signature) > sizeof(KVM_SIGNATURE));
> - if (!memcmp(signature, KVM_SIGNATURE, sizeof(signature))) {
> - vcpu->arch.kvm_cpuid_base = function;
> + if (!memcmp(signature, hypervisor_signature, sizeof(signature))) {
> + hypervisor_cpuid->base = function;
> + hypervisor_cpuid->limit = entry->eax;
> break;
> }
> }
> @@ -209,7 +210,7 @@ static void kvm_update_kvm_cpuid_base(struct kvm_vcpu *vcpu)
> static struct kvm_cpuid_entry2 *__kvm_find_kvm_cpuid_features(struct kvm_vcpu *vcpu,
> struct kvm_cpuid_entry2 *entries, int nent)
> {
> - u32 base = vcpu->arch.kvm_cpuid_base;
> + u32 base = vcpu->arch.kvm_cpuid.base;
>
> if (!base)
> return NULL;
> @@ -439,7 +440,7 @@ static int kvm_set_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2,
> vcpu->arch.cpuid_entries = e2;
> vcpu->arch.cpuid_nent = nent;
>
> - kvm_update_kvm_cpuid_base(vcpu);
> + kvm_update_hypervisor_cpuid(vcpu, KVM_SIGNATURE, &vcpu->arch.kvm_cpuid);
> kvm_vcpu_after_set_cpuid(vcpu);
>
> return 0;
© 2016 - 2026 Red Hat, Inc.