From: Eduardo Habkost <ehabkost@redhat.com>
To: Wanpeng Li <kernellwp@gmail.com>
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
"Borislav Petkov" <bp@alien8.de>,
LKML <linux-kernel@vger.kernel.org>, kvm <kvm@vger.kernel.org>,
"Radim Krčmář" <rkrcmar@redhat.com>
Subject: Re: [PATCH] KVM: X86: Allow userspace to define the microcode version
Date: Wed, 18 Apr 2018 06:03:29 -0300 [thread overview]
Message-ID: <20180418090329.GJ29865@localhost.localdomain> (raw)
In-Reply-To: <CANRm+CwA22VmpA5cfQg8mF_Xke_hXtP+_ui5xU+LV8v0JNj=3Q@mail.gmail.com>
On Wed, Apr 18, 2018 at 11:24:22AM +0800, Wanpeng Li wrote:
> 2018-04-18 4:24 GMT+08:00 Eduardo Habkost <ehabkost@redhat.com>:
> > On Tue, Apr 17, 2018 at 06:40:58PM +0800, Wanpeng Li wrote:
> >> Cc Eduardo,
> >> 2018-02-26 20:41 GMT+08:00 Paolo Bonzini <pbonzini@redhat.com>:
> >> > On 26/02/2018 13:22, Borislav Petkov wrote:
> >> >> On Mon, Feb 26, 2018 at 01:18:07PM +0100, Paolo Bonzini wrote:
> >> >>>> In this context, "host-initiated" write means written by KVM userspace
> >> >>>> with ioctl(KVM_SET_MSR). It generally happens only on VM startup, reset
> >> >>>> or live migration.
> >> >>>
> >> >>> To be clear, the target of the write is still the vCPU's emulated MSR.
> >> >>
> >> >> So how am I to imagine this as a user:
> >> >>
> >> >> qemu-system-x86_64 --microcode-revision=0xdeadbeef...
> >> >
> >> > More like "-cpu foo,ucode_rev=0xdeadbeef". But in practice what would
> >> > happen is one of the following:
> >> >
> >> > 1) "-cpu host" sets ucode_rev to the same value of the host, everyone
> >> > else leaves it to zero as is now.
> >>
> >> Hi Paolo,
> >>
> >> Do you mean the host admin to get the ucode_rev from the host and set
> >> to -cpu host, ucode_rev=xxxxxx or qemu get the ucode_rev directly by
> >> rdmsr?
> >
> > QEMU setting ucode_rev automatically using the host value when
> > using "-cpu host" (with no need for explicit ucode_rev option)
> > makes sense to me.
>
> QEMU can't get the host value by rdmsr MSR_IA32_UCODE_REV directly
> since rdmsr will #GP when ring !=0, any idea?
By looking at kvm_get_msr_feature(), it looks like
ioctl(system_fd, KVM_GET_MSRS) would return the host MSR value
for us.
--
Eduardo
next prev parent reply other threads:[~2018-04-18 9:03 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-26 7:23 [PATCH] KVM: X86: Allow userspace to define the microcode version Wanpeng Li
2018-02-26 9:41 ` Borislav Petkov
2018-02-26 10:06 ` Wanpeng Li
2018-02-26 10:49 ` Borislav Petkov
2018-02-26 11:02 ` Wanpeng Li
2018-02-26 11:16 ` Borislav Petkov
2018-02-26 11:25 ` Wanpeng Li
2018-02-26 11:30 ` Borislav Petkov
2018-02-26 11:37 ` Wanpeng Li
2018-02-26 11:44 ` Borislav Petkov
2018-02-26 11:52 ` Wanpeng Li
2018-02-26 11:54 ` Paolo Bonzini
2018-02-26 12:15 ` Borislav Petkov
2018-02-26 12:16 ` Paolo Bonzini
2018-02-26 12:18 ` Paolo Bonzini
2018-02-26 12:22 ` Borislav Petkov
2018-02-26 12:41 ` Paolo Bonzini
2018-02-26 13:05 ` Borislav Petkov
2018-02-26 14:39 ` Konrad Rzeszutek Wilk
2018-02-26 14:46 ` Paolo Bonzini
2018-02-26 19:37 ` Borislav Petkov
2018-02-26 20:51 ` Konrad Rzeszutek Wilk
2018-02-26 21:30 ` Konrad Rzeszutek Wilk
2018-02-27 8:33 ` Paolo Bonzini
2018-03-08 9:24 ` [tip:x86/pti] x86/spectre_v2: Don't check microcode versions when running under hypervisors tip-bot for Konrad Rzeszutek Wilk
2018-04-17 10:40 ` [PATCH] KVM: X86: Allow userspace to define the microcode version Wanpeng Li
2018-04-17 20:24 ` Eduardo Habkost
2018-04-18 3:24 ` Wanpeng Li
2018-04-18 9:03 ` Eduardo Habkost [this message]
2018-04-18 10:36 ` Paolo Bonzini
2018-04-23 12:58 ` Borislav Petkov
2018-04-23 13:08 ` Eduardo Habkost
2018-04-23 13:23 ` Borislav Petkov
2018-04-23 16:03 ` Paolo Bonzini
2018-04-24 2:59 ` Wanpeng Li
2018-04-24 3:14 ` Konrad Rzeszutek Wilk
2018-04-24 5:09 ` Paolo Bonzini
2018-04-24 13:44 ` Konrad Rzeszutek Wilk
2018-04-24 2:56 ` Wanpeng Li
2018-02-26 11:47 ` Paolo Bonzini
2018-02-26 12:20 ` Borislav Petkov
2018-02-26 9:26 Liran Alon
2018-02-26 10:08 ` Wanpeng Li
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