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Re: [PULL 15/22] x86: Grant AMX permission for guest
From: |
Daniel P . Berrangé |
Subject: |
Re: [PULL 15/22] x86: Grant AMX permission for guest |
Date: |
Wed, 16 Mar 2022 17:50:49 +0000 |
User-agent: |
Mutt/2.1.5 (2021-12-30) |
On Wed, Mar 16, 2022 at 05:48:04PM +0000, David Edmondson wrote:
> On Wednesday, 2022-03-16 at 16:05:01 GMT, Daniel P. Berrangé wrote:
>
> > On Wed, Mar 16, 2022 at 04:57:39PM +0100, Peter Krempa wrote:
> >> On Tue, Mar 08, 2022 at 12:34:38 +0100, Paolo Bonzini wrote:
> >> > From: Yang Zhong <yang.zhong@intel.com>
> >> >
> >> > Kernel allocates 4K xstate buffer by default. For XSAVE features
> >> > which require large state component (e.g. AMX), Linux kernel
> >> > dynamically expands the xstate buffer only after the process has
> >> > acquired the necessary permissions. Those are called dynamically-
> >> > enabled XSAVE features (or dynamic xfeatures).
> >> >
> >> > There are separate permissions for native tasks and guests.
> >> >
> >> > Qemu should request the guest permissions for dynamic xfeatures
> >> > which will be exposed to the guest. This only needs to be done
> >> > once before the first vcpu is created.
> >> >
> >> > KVM implemented one new ARCH_GET_XCOMP_SUPP system attribute API to
> >> > get host side supported_xcr0 and Qemu can decide if it can request
> >> > dynamically enabled XSAVE features permission.
> >> > https://lore.kernel.org/all/20220126152210.3044876-1-pbonzini@redhat.com/
> >> >
> >> > Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
> >> > Signed-off-by: Yang Zhong <yang.zhong@intel.com>
> >> > Signed-off-by: Jing Liu <jing2.liu@intel.com>
> >> > Message-Id: <20220217060434.52460-4-yang.zhong@intel.com>
> >> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> >> > ---
> >> > target/i386/cpu.c | 7 +++++
> >> > target/i386/cpu.h | 4 +++
> >> > target/i386/kvm/kvm-cpu.c | 12 ++++----
> >> > target/i386/kvm/kvm.c | 57 ++++++++++++++++++++++++++++++++++++++
> >> > target/i386/kvm/kvm_i386.h | 1 +
> >> > 5 files changed, 75 insertions(+), 6 deletions(-)
> >>
> >> With this commit qemu crashes for me when invoking the following
> >> QMP command:
> >
> > It is way worse than that even. If you remove '-S' you get an
> > immediate kaboom on startup on AMD hosts
>
> Which AMD CPU is in this host?
AMD EPYC 7302P
With regards,
Daniel
--
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- [PULL 09/22] kvm/msi: do explicit commit when adding msi routes, (continued)
- [PULL 09/22] kvm/msi: do explicit commit when adding msi routes, Paolo Bonzini, 2022/03/08
- [PULL 13/22] x86: Fix the 64-byte boundary enumeration for extended state, Paolo Bonzini, 2022/03/08
- [PULL 16/22] x86: Add XFD faulting bit for state components, Paolo Bonzini, 2022/03/08
- [PULL 18/22] x86: add support for KVM_CAP_XSAVE2 and AMX state migration, Paolo Bonzini, 2022/03/08
- [PULL 20/22] i386: Add Icelake-Server-v6 CPU model with 5-level EPT support, Paolo Bonzini, 2022/03/08
- [PULL 15/22] x86: Grant AMX permission for guest, Paolo Bonzini, 2022/03/08
- Re: [PULL 15/22] x86: Grant AMX permission for guest, Yang Zhong, 2022/03/17
- Re: [PULL 15/22] x86: Grant AMX permission for guest, Michal Prívozník, 2022/03/18
- Re: [PULL 15/22] x86: Grant AMX permission for guest, Yang Zhong, 2022/03/18
- Re: [PULL 15/22] x86: Grant AMX permission for guest, Yang Zhong, 2022/03/22
[PULL 11/22] target/i386: Throw a #SS when loading a non-canonical IST, Paolo Bonzini, 2022/03/08
[PULL 22/22] gitlab-ci: do not run tests with address sanitizer, Paolo Bonzini, 2022/03/08
[PULL 21/22] KVM: SVM: always set MSR_AMD64_TSC_RATIO to default value, Paolo Bonzini, 2022/03/08
[PULL 19/22] x86: Support XFD and AMX xsave data migration, Paolo Bonzini, 2022/03/08
Re: [PULL v2 00/22] QEMU changes for 7.0 soft freeze, Peter Maydell, 2022/03/10