From: Paolo Bonzini <pbonzini@redhat.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>, linmiaohe <linmiaohe@huawei.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
x86@kernel.org, rkrcmar@redhat.com,
sean.j.christopherson@intel.com, wanpengli@tencent.com,
jmattson@google.com, joro@8bytes.org, tglx@linutronix.de,
mingo@redhat.com, bp@alien8.de, hpa@zytor.com
Subject: Re: [PATCH] KVM: nVMX: set rflags to specify success in handle_invvpid() default case
Date: Thu, 23 Jan 2020 10:23:42 +0100 [thread overview]
Message-ID: <1a083ac8-3b01-fd2d-d867-2b3956cdef6d@redhat.com> (raw)
In-Reply-To: <8736c6sga7.fsf@vitty.brq.redhat.com>
On 23/01/20 09:55, Vitaly Kuznetsov wrote:
>> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
>> index 7608924ee8c1..985d3307ec56 100644
>> --- a/arch/x86/kvm/vmx/nested.c
>> +++ b/arch/x86/kvm/vmx/nested.c
>> @@ -5165,7 +5165,7 @@ static int handle_invvpid(struct kvm_vcpu *vcpu)
>> break;
>> default:
>> WARN_ON_ONCE(1);
>> - return kvm_skip_emulated_instruction(vcpu);
>> + break;
>> }
>>
>> return nested_vmx_succeed(vcpu);
> Your patch seems to do the right thing, however, I started wondering if
> WARN_ON_ONCE() is the right thing to do. SDM says that "If an
> unsupported INVVPID type is specified, the instruction fails." and this
> is similar to INVEPT and I decided to check what handle_invept()
> does. Well, it does BUG_ON().
>
> Are we doing the right thing in any of these cases?
Yes, both INVEPT and INVVPID catch this earlier.
For INVEPT:
types = (vmx->nested.msrs.ept_caps >> VMX_EPT_EXTENT_SHIFT) & 6;
if (type >= 32 || !(types & (1 << type)))
return nested_vmx_failValid(vcpu,
VMXERR_INVALID_OPERAND_TO_INVEPT_INVVPID);
For INVVPID:
types = (vmx->nested.msrs.vpid_caps &
VMX_VPID_EXTENT_SUPPORTED_MASK) >> 8;
if (type >= 32 || !(types & (1 << type)))
return nested_vmx_failValid(vcpu,
VMXERR_INVALID_OPERAND_TO_INVEPT_INVVPID);
So I'm leaning towards not applying Miaohe's patch. Happy Mouse Year
to everyone, here is an ASCII art (except for one Unicode character) mouse:
__()()
/ o)
~~~~\_,__,_>°
Thanks,
next prev parent reply other threads:[~2020-01-23 9:23 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-23 3:14 [PATCH] KVM: nVMX: set rflags to specify success in handle_invvpid() default case linmiaohe
2020-01-23 8:55 ` Vitaly Kuznetsov
2020-01-23 9:23 ` Paolo Bonzini [this message]
2020-01-23 9:45 ` Vitaly Kuznetsov
2020-01-23 9:54 ` Paolo Bonzini
2020-01-23 18:22 ` Jim Mattson
2020-01-23 23:01 ` Sean Christopherson
2020-01-24 10:53 ` Vitaly Kuznetsov
2020-01-23 9:36 linmiaohe
2020-02-03 3:29 linmiaohe
2020-02-03 9:48 ` Vitaly Kuznetsov
2020-02-04 1:06 linmiaohe
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