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From: Sean Christopherson <seanjc@google.com>
To: Zeng Guang <guang.zeng@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	H Peter Anvin <hpa@zytor.com>,
	kvm@vger.kernel.org, x86@kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1 2/6] KVM: x86: Virtualize CR4.LASS
Date: Wed, 16 Aug 2023 15:16:24 -0700	[thread overview]
Message-ID: <ZN1KuB3ZdD/E1tae@google.com> (raw)
In-Reply-To: <20230601142309.6307-3-guang.zeng@intel.com>

Belatedly, same complaints as the LAM series[*], this patch doesn't actually
virtual LASS.  Just squash this with the previous patch, "KVM: VMX: Implement and
apply vmx_is_lass_violation() for LASS protection", though I would keep the
shortlog from this patch.

[*] https://lore.kernel.org/all/ZN1CjTQ0zWiOxk6j@google.com

On Thu, Jun 01, 2023, Zeng Guang wrote:
> Virtualize CR4.LASS[bit 27] under KVM control instead of being guest-owned
> as CR4.LASS generally set once for each vCPU at boot time and won't be
> toggled at runtime. Besides, only if VM has LASS capability enumerated with
> CPUID.(EAX=07H.ECX=1):EAX.LASS[bit 6], KVM allows guest software to be able
> to set CR4.LASS.
> 
> Updating cr4_fixed1 to set CR4.LASS bit in the emulated IA32_VMX_CR4_FIXED1
> MSR for guests and allow guests to enable LASS in nested VMX operaion as well.
> 
> Notes: Setting CR4.LASS to 1 enable LASS in IA-32e mode. It doesn't take
> effect in legacy mode even if CR4.LASS is set.
> 
> Signed-off-by: Zeng Guang <guang.zeng@intel.com>
> Tested-by: Xuelian Guo <xuelian.guo@intel.com>

  parent reply	other threads:[~2023-08-16 22:17 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-01 14:23 [PATCH v1 0/6] LASS KVM virtualization support Zeng Guang
2023-06-01 14:23 ` [PATCH v1 1/6] KVM: x86: Consolidate flags for __linearize() Zeng Guang
2023-06-27 17:40   ` Sean Christopherson
2023-06-28  5:13     ` Binbin Wu
2023-06-28  7:27     ` Zeng Guang
2023-06-01 14:23 ` [PATCH v1 2/6] KVM: x86: Virtualize CR4.LASS Zeng Guang
2023-06-05  1:57   ` Binbin Wu
2023-06-06  2:57     ` Zeng Guang
2023-06-27 17:43   ` Sean Christopherson
2023-06-28  8:19     ` Zeng Guang
2023-08-16 22:16   ` Sean Christopherson [this message]
2023-06-01 14:23 ` [PATCH v1 3/6] KVM: VMX: Add new ops in kvm_x86_ops for LASS violation check Zeng Guang
2023-06-05  3:31   ` Binbin Wu
2023-06-05 12:53     ` Zhi Wang
2023-06-06  2:57       ` Binbin Wu
2023-06-06  3:53         ` Zhi Wang
2023-06-07  6:28     ` Zeng Guang
2023-06-05  3:47   ` Chao Gao
2023-06-06  6:22     ` Zeng Guang
2023-06-05 14:07   ` Yuan Yao
2023-06-06  3:08     ` Zeng Guang
2023-06-27 18:26   ` Sean Christopherson
2023-06-27 22:45     ` Sean Christopherson
2023-06-30 18:50     ` Zeng Guang
2023-06-01 14:23 ` [PATCH v1 4/6] KVM: x86: Add emulator helper " Zeng Guang
2023-06-27 18:28   ` Sean Christopherson
2023-06-29 15:06     ` Zeng Guang
2023-06-01 14:23 ` [PATCH v1 5/6] KVM: x86: LASS protection on KVM emulation Zeng Guang
2023-06-06  4:20   ` Binbin Wu
2023-06-01 14:23 ` [PATCH v1 6/6] KVM: x86: Advertise LASS CPUID to user space Zeng Guang
2023-06-02  0:35 ` [PATCH v1 0/6] LASS KVM virtualization support Sean Christopherson
2023-06-06  2:22   ` Zeng Guang
2023-06-05  1:39 ` Binbin Wu
2023-06-06  2:40   ` Zeng Guang
2023-06-27 17:08 ` Sean Christopherson
2023-06-28  8:42   ` Zeng Guang

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