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Re: [Qemu-devel] [PULL 09/12] i386: Allow TOPOEXT to be enabled on older
From: |
Richard W.M. Jones |
Subject: |
Re: [Qemu-devel] [PULL 09/12] i386: Allow TOPOEXT to be enabled on older kernels |
Date: |
Thu, 9 Aug 2018 21:29:52 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Mon, Jun 25, 2018 at 07:25:21PM -0300, Eduardo Habkost wrote:
> From: Babu Moger <address@hidden>
>
> Enabling TOPOEXT feature might cause compatibility issues if
> older kernels does not set this feature. Lets set this feature
> unconditionally.
>
> Signed-off-by: Babu Moger <address@hidden>
> Message-Id: <address@hidden>
> [ehabkost: rewrite comment and commit message]
> Signed-off-by: Eduardo Habkost <address@hidden>
> ---
> target/i386/kvm.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/target/i386/kvm.c b/target/i386/kvm.c
> index 445e0e0b11..2d174f3a91 100644
> --- a/target/i386/kvm.c
> +++ b/target/i386/kvm.c
> @@ -372,6 +372,13 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s,
> uint32_t function,
> if (host_tsx_blacklisted()) {
> ret &= ~(CPUID_7_0_EBX_RTM | CPUID_7_0_EBX_HLE);
> }
> + } else if (function == 0x80000001 && reg == R_ECX) {
> + /*
> + * It's safe to enable TOPOEXT even if it's not returned by
> + * GET_SUPPORTED_CPUID. Unconditionally enabling TOPOEXT here allows
> + * us to keep CPU models including TOPOEXT runnable on older kernels.
> + */
> + ret |= CPUID_EXT3_TOPOEXT;
> } else if (function == 0x80000001 && reg == R_EDX) {
> /* On Intel, kvm returns cpuid according to the Intel spec,
> * so add missing bits according to the AMD spec:
This commit breaks KVM (not TCG) with -cpu host on:
AMD Phenom(tm) 9600B Quad-Core Processor
More details including full qemu command line etc in this bug:
https://bugzilla.redhat.com/show_bug.cgi?id=1613277
Rich.
--
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