From: Borislav Petkov <bp@suse.de>
To: speck@linutronix.de
Subject: [MODERATED] Re: [patch V6 12/14] MDS basics 12
Date: Wed, 6 Mar 2019 15:42:46 +0100 [thread overview]
Message-ID: <20190306144246.GG21338@zn.tnic> (raw)
In-Reply-To: <20190301214848.253554490@linutronix.de>
On Fri, Mar 01, 2019 at 10:47:50PM +0100, speck for Thomas Gleixner wrote:
> Subject: [patch V6 12/14] x86/speculation/mds: Add mitigation mode VMWERV
> From: Thomas Gleixner <tglx@linutronix.de>
>
> In virtualized environments it can happen that the host has the microcode
> update which utilizes the VERW instruction to clear CPU buffers, but the
> hypervisor is not yet updated to expose the X86_FEATURE_MD_CLEAR CPUID bit
> to guests.
>
> Introduce an internal mitigation mode VWWERV which enables the invocation
> of the CPU buffer clearing even if X86_FEATURE_MD_CLEAR is not set. If the
> system has no updated microcode this results in a pointless execution of
> the VERW instruction wasting a few CPU cycles. If the microcode is updated,
> but not exposed to a guest then the CPU buffers will be cleared.
>
> That said: Virtual Machines Will Eventually Receive Vaccine
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
> V2 -> V3: Rename mode.
> ---
> Documentation/x86/mds.rst | 27 +++++++++++++++++++++++++++
> arch/x86/include/asm/processor.h | 1 +
> arch/x86/kernel/cpu/bugs.c | 18 ++++++++++++------
> 3 files changed, 40 insertions(+), 6 deletions(-)
...
> @@ -235,10 +236,9 @@ static void mds_select_mitigation(void)
> }
>
> if (mds_mitigation == MDS_MITIGATION_FULL) {
> - if (boot_cpu_has(X86_FEATURE_MD_CLEAR))
> - static_branch_enable(&mds_user_clear);
> - else
> - mds_mitigation = MDS_MITIGATION_OFF;
> + if (!boot_cpu_has(X86_FEATURE_MD_CLEAR))
> + mds_mitigation = MDS_MITIGATION_VMWERV;
> + static_branch_enable(&mds_user_clear);
> }
> pr_info("%s\n", mds_strings[mds_mitigation]);
> }
> @@ -703,8 +703,14 @@ void arch_smt_update(void)
> break;
> }
>
> - if (mds_mitigation == MDS_MITIGATION_FULL)
> + switch(mds_mitigation) {
ERROR: space required before the open parenthesis '('
#119: FILE: arch/x86/kernel/cpu/bugs.c:706:
+ switch(mds_mitigation) {
with that addressed:
Reviewed-by: Borislav Petkov <bp@suse.de>
--
Regards/Gruss,
Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--
next prev parent reply other threads:[~2019-03-06 14:42 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-01 21:47 [patch V6 00/14] MDS basics 0 Thomas Gleixner
2019-03-01 21:47 ` [patch V6 01/14] MDS basics 1 Thomas Gleixner
2019-03-02 0:06 ` [MODERATED] " Frederic Weisbecker
2019-03-01 21:47 ` [patch V6 02/14] MDS basics 2 Thomas Gleixner
2019-03-02 0:34 ` [MODERATED] " Frederic Weisbecker
2019-03-02 8:34 ` Greg KH
2019-03-05 17:54 ` Borislav Petkov
2019-03-01 21:47 ` [patch V6 03/14] MDS basics 3 Thomas Gleixner
2019-03-02 1:12 ` [MODERATED] " Frederic Weisbecker
2019-03-01 21:47 ` [patch V6 04/14] MDS basics 4 Thomas Gleixner
2019-03-02 1:28 ` [MODERATED] " Frederic Weisbecker
2019-03-05 14:52 ` Thomas Gleixner
2019-03-06 20:00 ` [MODERATED] " Andrew Cooper
2019-03-06 20:32 ` Thomas Gleixner
2019-03-07 23:56 ` [MODERATED] " Andi Kleen
2019-03-08 0:36 ` Linus Torvalds
2019-03-01 21:47 ` [patch V6 05/14] MDS basics 5 Thomas Gleixner
2019-03-02 1:37 ` [MODERATED] " Frederic Weisbecker
2019-03-07 23:59 ` Andi Kleen
2019-03-08 6:37 ` Thomas Gleixner
2019-03-01 21:47 ` [patch V6 06/14] MDS basics 6 Thomas Gleixner
2019-03-04 6:28 ` [MODERATED] Encrypted Message Jon Masters
2019-03-05 14:55 ` Thomas Gleixner
2019-03-01 21:47 ` [patch V6 07/14] MDS basics 7 Thomas Gleixner
2019-03-02 2:22 ` [MODERATED] " Frederic Weisbecker
2019-03-05 15:30 ` Thomas Gleixner
2019-03-06 15:49 ` [MODERATED] " Frederic Weisbecker
2019-03-06 5:21 ` Borislav Petkov
2019-03-01 21:47 ` [patch V6 08/14] MDS basics 8 Thomas Gleixner
2019-03-03 2:54 ` [MODERATED] " Frederic Weisbecker
2019-03-04 6:57 ` [MODERATED] Encrypted Message Jon Masters
2019-03-04 7:06 ` Jon Masters
2019-03-04 8:12 ` Jon Masters
2019-03-05 15:34 ` Thomas Gleixner
2019-03-06 16:21 ` [MODERATED] " Jon Masters
2019-03-06 14:11 ` [MODERATED] Re: [patch V6 08/14] MDS basics 8 Borislav Petkov
2019-03-01 21:47 ` [patch V6 09/14] MDS basics 9 Thomas Gleixner
2019-03-06 16:14 ` [MODERATED] " Frederic Weisbecker
2019-03-01 21:47 ` [patch V6 10/14] MDS basics 10 Thomas Gleixner
2019-03-04 6:45 ` [MODERATED] Encrypted Message Jon Masters
2019-03-05 18:42 ` [MODERATED] Re: [patch V6 10/14] MDS basics 10 Andrea Arcangeli
2019-03-06 19:15 ` Thomas Gleixner
2019-03-06 14:31 ` [MODERATED] " Borislav Petkov
2019-03-06 15:30 ` Thomas Gleixner
2019-03-06 18:35 ` Thomas Gleixner
2019-03-06 19:34 ` [MODERATED] Re: " Borislav Petkov
2019-03-01 21:47 ` [patch V6 11/14] MDS basics 11 Thomas Gleixner
2019-03-01 21:47 ` [patch V6 12/14] MDS basics 12 Thomas Gleixner
2019-03-04 5:47 ` [MODERATED] Encrypted Message Jon Masters
2019-03-05 16:04 ` Thomas Gleixner
2019-03-05 16:40 ` [MODERATED] Re: [patch V6 12/14] MDS basics 12 mark gross
2019-03-06 14:42 ` Borislav Petkov [this message]
2019-03-01 21:47 ` [patch V6 13/14] MDS basics 13 Thomas Gleixner
2019-03-03 4:01 ` [MODERATED] " Josh Poimboeuf
2019-03-05 16:04 ` Thomas Gleixner
2019-03-05 16:43 ` [MODERATED] " mark gross
2019-03-01 21:47 ` [patch V6 14/14] MDS basics 14 Thomas Gleixner
2019-03-01 23:48 ` [patch V6 00/14] MDS basics 0 Thomas Gleixner
2019-03-04 5:30 ` [MODERATED] Encrypted Message Jon Masters
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