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From: Paolo Bonzini <pbonzini@redhat.com>
To: "Yang, Weijiang" <weijiang.yang@intel.com>
Cc: Sean Christopherson <seanjc@google.com>,
	peterz@infradead.org, john.allen@amd.com, kvm@vger.kernel.org,
	linux-kernel@vger.kernel.org, rick.p.edgecombe@intel.com,
	chao.gao@intel.com, binbin.wu@linux.intel.com,
	Zhang Yi Z <yi.z.zhang@linux.intel.com>
Subject: Re: [PATCH v5 04/19] KVM:x86: Refresh CPUID on write to guest MSR_IA32_XSS
Date: Thu, 10 Aug 2023 02:01:29 +0200	[thread overview]
Message-ID: <CABgObfbvr8F8g5hJN6jn95m7u7m2+8ACkqO25KAZwRmJ9AncZg@mail.gmail.com> (raw)
In-Reply-To: <0655c963-78e5-62c9-50af-20d9de8a1001@intel.com>

On Wed, Aug 9, 2023 at 10:56 AM Yang, Weijiang <weijiang.yang@intel.com> wrote:
> > I'm pretty sure I've advocated for the exact opposite in the past, i.e. argued
> > that KVM's ABI is to not enforce ordering between KVM_SET_CPUID2 and KVM_SET_MSR.
> > But this is becoming untenable, juggling the dependencies in KVM is complex and
> > is going to result in a nasty bug at some point.
> >
> > For this series, lets just tighten the rules for XSS, i.e. drop the host_initated
> > exemption.  And in a parallel/separate series, try to do a wholesale cleanup of
> > all the cases that essentially allow userspace to do KVM_SET_MSR before KVM_SET_CPUID2.
> OK, will do it for this series and investigate for other MSRs.
> Thanks!

Remember that, while the ordering between KVM_SET_CPUID2 and
KVM_SET_MSR must be enforced(*), the host_initiated path must allow
the default (generally 0) value.

Paolo

(*) this means that you should check guest_cpuid_has even if
host_initiated == true.


  reply	other threads:[~2023-08-10  0:02 UTC|newest]

Thread overview: 82+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-03  4:27 [PATCH v5 00/19] Enable CET Virtualization Yang Weijiang
2023-08-03  4:27 ` [PATCH v5 01/19] x86/cpufeatures: Add CPU feature flags for shadow stacks Yang Weijiang
2023-08-03  4:27 ` [PATCH v5 02/19] x86/fpu/xstate: Introduce CET MSR and XSAVES supervisor states Yang Weijiang
2023-08-03  4:27 ` [PATCH v5 03/19] KVM:x86: Report XSS as to-be-saved if there are supported features Yang Weijiang
2023-08-03  4:27 ` [PATCH v5 04/19] KVM:x86: Refresh CPUID on write to guest MSR_IA32_XSS Yang Weijiang
2023-08-04 16:02   ` Sean Christopherson
2023-08-04 21:43     ` Paolo Bonzini
2023-08-09  3:11       ` Yang, Weijiang
2023-08-08 14:20     ` Yang, Weijiang
2023-08-04 18:27   ` Sean Christopherson
2023-08-07  6:55     ` Paolo Bonzini
2023-08-09  8:56     ` Yang, Weijiang
2023-08-10  0:01       ` Paolo Bonzini [this message]
2023-08-10  1:12         ` Yang, Weijiang
2023-08-03  4:27 ` [PATCH v5 05/19] KVM:x86: Initialize kvm_caps.supported_xss Yang Weijiang
2023-08-04 18:45   ` Sean Christopherson
2023-08-08 15:08     ` Yang, Weijiang
2023-08-03  4:27 ` [PATCH v5 06/19] KVM:x86: Load guest FPU state when access XSAVE-managed MSRs Yang Weijiang
2023-08-03  4:27 ` [PATCH v5 07/19] KVM:x86: Add fault checks for guest CR4.CET setting Yang Weijiang
2023-08-03  9:07   ` Chao Gao
2023-08-03  4:27 ` [PATCH v5 08/19] KVM:x86: Report KVM supported CET MSRs as to-be-saved Yang Weijiang
2023-08-03 10:39   ` Chao Gao
2023-08-04  3:13     ` Yang, Weijiang
2023-08-04  5:51       ` Chao Gao
2023-08-04 18:51         ` Sean Christopherson
2023-08-04 22:01           ` Paolo Bonzini
2023-08-08 15:16           ` Yang, Weijiang
2023-08-06  8:54         ` Yang, Weijiang
2023-08-04 18:55   ` Sean Christopherson
2023-08-08 15:26     ` Yang, Weijiang
2023-08-04 21:47   ` Paolo Bonzini
2023-08-09  3:14     ` Yang, Weijiang
2023-08-03  4:27 ` [PATCH v5 09/19] KVM:x86: Make guest supervisor states as non-XSAVE managed Yang Weijiang
2023-08-03 11:15   ` Chao Gao
2023-08-04  3:26     ` Yang, Weijiang
2023-08-04 20:45       ` Sean Christopherson
2023-08-04 20:59         ` Peter Zijlstra
2023-08-04 21:32         ` Paolo Bonzini
2023-08-09  2:51           ` Yang, Weijiang
2023-08-09  2:39         ` Yang, Weijiang
2023-08-10  9:29         ` Yang, Weijiang
2023-08-10 14:29           ` Dave Hansen
2023-08-10 15:15             ` Paolo Bonzini
2023-08-10 15:37               ` Sean Christopherson
2023-08-11  3:03               ` Yang, Weijiang
2023-08-28 21:00               ` Dave Hansen
2023-08-29  7:05                 ` Yang, Weijiang
2023-08-03  4:27 ` [PATCH v5 10/19] KVM:VMX: Introduce CET VMCS fields and control bits Yang Weijiang
2023-08-03  4:27 ` [PATCH v5 11/19] KVM:VMX: Emulate read and write to CET MSRs Yang Weijiang
2023-08-04  5:14   ` Chao Gao
2023-08-04 21:27     ` Sean Christopherson
2023-08-04 21:45       ` Paolo Bonzini
2023-08-04 22:21         ` Sean Christopherson
2023-08-07  7:03           ` Paolo Bonzini
2023-08-06  8:44       ` Yang, Weijiang
2023-08-07  7:00         ` Paolo Bonzini
2023-08-04  8:28   ` Chao Gao
2023-08-09  7:12     ` Yang, Weijiang
2023-08-04 21:40   ` Paolo Bonzini
2023-08-09  3:05     ` Yang, Weijiang
2023-08-03  4:27 ` [PATCH v5 12/19] KVM:x86: Save and reload SSP to/from SMRAM Yang Weijiang
2023-08-04  7:53   ` Chao Gao
2023-08-04 15:25     ` Sean Christopherson
2023-08-06  9:14       ` Yang, Weijiang
2023-08-03  4:27 ` [PATCH v5 13/19] KVM:VMX: Set up interception for CET MSRs Yang Weijiang
2023-08-04  8:16   ` Chao Gao
2023-08-06  9:22     ` Yang, Weijiang
2023-08-07  1:16       ` Chao Gao
2023-08-09  6:11         ` Yang, Weijiang
2023-08-03  4:27 ` [PATCH v5 14/19] KVM:VMX: Set host constant supervisor states to VMCS fields Yang Weijiang
2023-08-04  8:23   ` Chao Gao
2023-08-03  4:27 ` [PATCH v5 15/19] KVM:x86: Optimize CET supervisor SSP save/reload Yang Weijiang
2023-08-04  8:43   ` Chao Gao
2023-08-09  9:00     ` Yang, Weijiang
2023-08-03  4:27 ` [PATCH v5 16/19] KVM:x86: Enable CET virtualization for VMX and advertise to userspace Yang Weijiang
2023-08-03  4:27 ` [PATCH v5 17/19] KVM:x86: Enable guest CET supervisor xstate bit support Yang Weijiang
2023-08-04 22:02   ` Paolo Bonzini
2023-08-09  6:07     ` Yang, Weijiang
2023-08-03  4:27 ` [PATCH v5 18/19] KVM:nVMX: Refine error code injection to nested VM Yang Weijiang
2023-08-04 21:38   ` Sean Christopherson
2023-08-09  3:00     ` Yang, Weijiang
2023-08-03  4:27 ` [PATCH v5 19/19] KVM:nVMX: Enable CET support for " Yang Weijiang

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