From: Paolo Bonzini <pbonzini@redhat.com>
To: Jim Mattson <jmattson@google.com>, Wanpeng Li <kernellwp@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
"kvm list" <kvm@vger.kernel.org>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Wanpeng Li" <wanpeng.li@hotmail.com>
Subject: Re: [PATCH v2 1/2] KVM: VMX: Don't advertise EPT switching if EPT itself is not exposed
Date: Tue, 17 Oct 2017 19:35:48 +0200 [thread overview]
Message-ID: <f60cbdeb-442f-8151-7b13-833ee8a4dc79@redhat.com> (raw)
In-Reply-To: <CALMp9eRG902CG4kAq19a3dGRMcQyJ1Le9osLF1QcoqLdyRKdbw@mail.gmail.com>
On 17/10/2017 19:29, Jim Mattson wrote:
> Following the same line of reasoning, what if
> vmx->nested.nested_vmx_secondary_ctls_high is 0 after clearing
> SECONDARY_EXEC_ENABLE_VMFUNC? Does it make sense to report
> CPU_BASED_ACTIVATE_SECONDARY_CONTROLS if we don't actually support any
> of the secondary controls?
All-zero is a valid value for secondary controls, so I think yes. Besides:
1) userspace can always get into a situation where there are no valid
secondary controls but processor-based execution controls have bit 31 as
1-allowed;
2) I doubt that vmfunc can be the one bit that causes
nested_vmx_secondary_ctls_high to become zero :)
Paolo
next prev parent reply other threads:[~2017-10-17 17:35 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-17 4:03 Wanpeng Li
2017-10-17 4:03 ` [PATCH v2 2/2] KVM: VMX: Fix VPID capability detection Wanpeng Li
2017-10-17 17:43 ` Jim Mattson
2017-10-17 17:48 ` Paolo Bonzini
2017-10-18 0:51 ` Wanpeng Li
2017-10-17 17:29 ` [PATCH v2 1/2] KVM: VMX: Don't advertise EPT switching if EPT itself is not exposed Jim Mattson
2017-10-17 17:35 ` Paolo Bonzini [this message]
2017-10-17 18:30 ` Jim Mattson
2017-10-18 1:05 ` Wanpeng Li
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