From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
To: Jan Beulich <JBeulich@suse.com>, Ashok Raj <ashok.raj@intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>, Wei Liu <wei.liu2@citrix.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Jun Nakajima <jun.nakajima@intel.com>,
xen-devel <xen-devel@lists.xenproject.org>,
tglx@linutronix.de, Borislav Petkov <bp@suse.de>,
Chao Gao <chao.gao@intel.com>
Subject: Re: [PATCH v4 6/6] x86/microcode: Synchronize late microcode loading
Date: Wed, 12 Dec 2018 21:10:50 -0500 [thread overview]
Message-ID: <ceb7b059-b9d9-7c3a-8fbc-bb0e0bfa79e2@oracle.com> (raw)
In-Reply-To: <5C10B8200200007800205515@prv1-mh.provo.novell.com>
On 12/12/18 2:26 AM, Jan Beulich wrote:
>>>> On 11.12.18 at 19:16, <ashok.raj@intel.com> wrote:
>> BTW: Apart from the fact its ugly and take a loooong time to complete, do you
>> have any practical isssues you want to highlight? maybe that can
>> help upstream as well.
> The situation for a kernel and a hypervisor might be different here
> (but in the Linux case may then be more hypervisor-like when
> considering KVM): The hypervisor needs to make sure in particular
> time management within guests won't break. Stopping the
> machine for an extended period of time may not be helpful there.
> For processes in an OS the constraints might not be as tight, but
> I could imaging problems even there in some less common cases.
>
> That said, I'm not convinced at all it is a good idea to load new
> ucode while _any_ guests are running, but we're talking about a
> last resort approach here anyway.
>
BTW, one thing I meant to mention about this patch earlier: we observed
that updating microcode from only one sibling resulted in guest reading
stale version value from another thread. This causes at least some
Windows versions to crash.
We ended up executing "wrmsr(0x8b, 0); cpuid_eax(1);" on all threads
after the update. (Another alternative could be to intercept the reads)
-boris
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next prev parent reply other threads:[~2018-12-13 2:11 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-28 5:34 [PATCH v4 0/6] improve late microcode loading Chao Gao
2018-11-28 5:34 ` [PATCH v4 1/6] microcode/intel: extend microcode_update_match() Chao Gao
2018-11-28 10:58 ` Roger Pau Monné
2018-11-29 2:00 ` Chao Gao
2018-11-29 9:14 ` Roger Pau Monné
2018-11-28 5:34 ` [PATCH v4 2/6] microcode: save all microcodes which pass sanity check Chao Gao
2018-11-28 12:00 ` Roger Pau Monné
2018-11-29 2:40 ` Chao Gao
2018-11-29 9:22 ` Roger Pau Monné
2018-11-30 7:55 ` Chao Gao
2018-11-30 9:32 ` Jan Beulich
2019-01-15 15:07 ` Andrew Cooper
2018-12-04 22:39 ` Woods, Brian
2018-12-05 7:38 ` Chao Gao
2018-11-29 10:19 ` Jan Beulich
2019-01-15 15:15 ` Andrew Cooper
2018-11-28 5:34 ` [PATCH v4 3/6] microcode: delete 'mc' field from struct ucode_cpu_info Chao Gao
2018-11-28 12:32 ` Roger Pau Monné
2018-11-28 5:34 ` [PATCH v4 4/6] microcode: don't call apply_microcode() in cpu_request_microcode() Chao Gao
2018-11-28 15:02 ` Roger Pau Monné
2018-11-29 4:28 ` Chao Gao
2018-11-29 9:46 ` Roger Pau Monné
2018-11-30 8:57 ` Chao Gao
2018-11-30 9:38 ` Jan Beulich
2018-11-28 5:34 ` [PATCH v4 5/6] microcode: delete microcode pointer and size from microcode_info Chao Gao
2018-11-28 15:04 ` Roger Pau Monné
2018-11-28 5:34 ` [PATCH v4 6/6] x86/microcode: Synchronize late microcode loading Chao Gao
2018-11-28 15:22 ` Roger Pau Monné
2018-11-29 4:43 ` Chao Gao
2018-11-29 9:56 ` Roger Pau Monné
2018-11-29 22:43 ` Boris Ostrovsky
2018-11-30 9:46 ` Jan Beulich
2018-11-30 16:49 ` Boris Ostrovsky
2018-11-30 9:01 ` Chao Gao
2019-01-15 15:24 ` Andrew Cooper
2019-01-15 16:24 ` Roger Pau Monné
2018-12-11 17:01 ` Jan Beulich
2018-12-11 18:16 ` Raj, Ashok
2018-12-12 7:26 ` Jan Beulich
2018-12-13 2:10 ` Boris Ostrovsky [this message]
2018-12-12 4:53 ` Chao Gao
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