linux-kernel - Re: [PATCH v1 1/1] KVM: x86: Advertise support for LKGS

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Message-ID: <175218111367.1487754.6051373868234671503.b4-ty@google.com>
Date: Thu, 10 Jul 2025 16:08:52 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, linux-kernel@...r.kernel.org, kvm@...r.kernel.org, 
	"Xin Li (Intel)" <xin@...or.com>
Cc: pbonzini@...hat.com, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, 
	dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com, 
	chao.gao@...el.com
Subject: Re: [PATCH v1 1/1] KVM: x86: Advertise support for LKGS

On Thu, 26 Jun 2025 10:35:21 -0700, Xin Li (Intel) wrote:
> Advertise support for LKGS (load into IA32_KERNEL_GS_BASE) to userspace
> if the instruction is supported by the underlying CPU.
> 
> LKGS is introduced with FRED to completely eliminate the need to swapgs
> explicilty.  It behaves like the MOV to GS instruction except that it
> loads the base address into the IA32_KERNEL_GS_BASE MSR instead of the
> GS segment’s descriptor cache, which is exactly what Linux kernel does
> to load a user level GS base.  Thus there is no need to SWAPGS away
> from the kernel GS base.
> 
> [...]

Applied to kvm-x86 misc, thanks!

[1/1] KVM: x86: Advertise support for LKGS
      https://github.com/kvm-x86/linux/commit/e88cfd50b606

--
https://github.com/kvm-x86/linux/tree/next