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Re: [Qemu-devel] [PATCH] i386: Disable TOPOEXT by default on "-cpu host"
From: |
Richard W.M. Jones |
Subject: |
Re: [Qemu-devel] [PATCH] i386: Disable TOPOEXT by default on "-cpu host" |
Date: |
Fri, 10 Aug 2018 08:41:10 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Thu, Aug 09, 2018 at 07:18:52PM -0300, Eduardo Habkost wrote:
> Enabling TOPOEXT is always allowed, but it can't be enabled
> blindly by "-cpu host" because it may make guests crash if the
> rest of the cache topology information isn't provided or isn't
> consistent.
>
> This addresses the bug reported at:
> https://bugzilla.redhat.com/show_bug.cgi?id=1613277
>
> Signed-off-by: Eduardo Habkost <address@hidden>
> ---
> target/i386/cpu.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index 723e02221e..3ac627978f 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -849,6 +849,12 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS]
> = {
> },
> .cpuid_eax = 0x80000001, .cpuid_reg = R_ECX,
> .tcg_features = TCG_EXT3_FEATURES,
> + /*
> + * TOPOEXT is always allowed but can't be enabled blindly by
> + * "-cpu host", as it requires consistent cache topology info
> + * to be provided so it doesn't confuse guests.
> + */
> + .no_autoenable_flags = CPUID_EXT3_TOPOEXT,
> },
> [FEAT_C000_0001_EDX] = {
> .feat_names = {
Can confirm that this fixes the problem observed on the original AMD
Phenom machine, using qemu from git (@6ad908053) + your patch.
Therefore:
Tested-by: Richard W.M. Jones <address@hidden>
Thanks,
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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