Re: [PATCH v2 1/7] KVM: X86: Reset vcpu->arch.cpuid_nent to 0 if SET_CPUID fails

2020-06-23 Thread Xiaoyao Li 

On 6/24/2020 2:20 AM, Jim Mattson wrote:

On Tue, Jun 23, 2020 at 4:58 AM Xiaoyao Li  wrote:


It needs to invalidate CPUID configruations if usersapce provides


Nits: configurations, userspace


oh, I'll fix it.


illegal input.

Signed-off-by: Xiaoyao Li 
---
  arch/x86/kvm/cpuid.c | 4 
  1 file changed, 4 insertions(+)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 8a294f9747aa..1d13bad42bf9 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -207,6 +207,8 @@ int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
 kvm_apic_set_version(vcpu);
 kvm_x86_ops.cpuid_update(vcpu);
 r = kvm_update_cpuid(vcpu);
+   if (r)
+   vcpu->arch.cpuid_nent = 0;

 kvfree(cpuid_entries);
  out:
@@ -230,6 +232,8 @@ int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu,
 kvm_apic_set_version(vcpu);
 kvm_x86_ops.cpuid_update(vcpu);
 r = kvm_update_cpuid(vcpu);
+   if (r)
+   vcpu->arch.cpuid_nent = 0;
  out:
 return r;
  }
--
2.18.2


What if vcpu->arch.cpuid_nent was greater than 0 before the ioctl in question?



Nice catch!

If considering it, then we have to restore the old CPUID configuration. 
So how about making it simpler to just add one line of comment in API doc:
If KVM_SET_CPUID{2} fails, the old valid configuration is cleared as a 
side effect.

Re: [PATCH v2 1/7] KVM: X86: Reset vcpu->arch.cpuid_nent to 0 if SET_CPUID fails

2020-06-23 Thread Jim Mattson 
On Tue, Jun 23, 2020 at 4:58 AM Xiaoyao Li  wrote:
>
> It needs to invalidate CPUID configruations if usersapce provides

Nits: configurations, userspace

> illegal input.
>
> Signed-off-by: Xiaoyao Li 
> ---
>  arch/x86/kvm/cpuid.c | 4 
>  1 file changed, 4 insertions(+)
>
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 8a294f9747aa..1d13bad42bf9 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -207,6 +207,8 @@ int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
> kvm_apic_set_version(vcpu);
> kvm_x86_ops.cpuid_update(vcpu);
> r = kvm_update_cpuid(vcpu);
> +   if (r)
> +   vcpu->arch.cpuid_nent = 0;
>
> kvfree(cpuid_entries);
>  out:
> @@ -230,6 +232,8 @@ int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu,
> kvm_apic_set_version(vcpu);
> kvm_x86_ops.cpuid_update(vcpu);
> r = kvm_update_cpuid(vcpu);
> +   if (r)
> +   vcpu->arch.cpuid_nent = 0;
>  out:
> return r;
>  }
> --
> 2.18.2

What if vcpu->arch.cpuid_nent was greater than 0 before the ioctl in question?

[PATCH v2 1/7] KVM: X86: Reset vcpu->arch.cpuid_nent to 0 if SET_CPUID fails

2020-06-23 Thread Xiaoyao Li 
It needs to invalidate CPUID configruations if usersapce provides
illegal input.

Signed-off-by: Xiaoyao Li 
---
 arch/x86/kvm/cpuid.c | 4 
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 8a294f9747aa..1d13bad42bf9 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -207,6 +207,8 @@ int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
kvm_apic_set_version(vcpu);
kvm_x86_ops.cpuid_update(vcpu);
r = kvm_update_cpuid(vcpu);
+   if (r)
+   vcpu->arch.cpuid_nent = 0;
 
kvfree(cpuid_entries);
 out:
@@ -230,6 +232,8 @@ int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu,
kvm_apic_set_version(vcpu);
kvm_x86_ops.cpuid_update(vcpu);
r = kvm_update_cpuid(vcpu);
+   if (r)
+   vcpu->arch.cpuid_nent = 0;
 out:
return r;
 }
-- 
2.18.2