linux-kernel - Re: [PATCH 0/8] KVM: SVM: Clean up VMRUN=>#VMEXIT assembly

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Message-ID: <171270505394.1590014.8020716629474398619.b4-ty@google.com>
Date: Tue,  9 Apr 2024 17:19:59 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Tom Lendacky <thomas.lendacky@....com>, Michael Roth <michael.roth@....com>, 
	Alexey Kardashevskiy <aik@....com>
Subject: Re: [PATCH 0/8] KVM: SVM: Clean up VMRUN=>#VMEXIT assembly

On Fri, 23 Feb 2024 12:42:25 -0800, Sean Christopherson wrote:
> Clean up SVM's enter/exit assembly code so that it can be compiled
> without OBJECT_FILES_NON_STANDARD.  The "standard" __svm_vcpu_run() can't
> be made 100% bulletproof, as RBP isn't restored on #VMEXIT, but that's
> also the case for __vmx_vcpu_run(), and getting "close enough" is better
> than not even trying.
> 
> As for SEV-ES, after yet another refresher on swap types, I realized KVM
> can simply let the hardware restore registers after #VMEXIT, all that's
> missing is storing the current values to the host save area (I learned the
> hard way that they are swap Type B, *sigh*).  Unless I'm missing something,
> this provides 100% accuracy when using stack frames for unwinding, and
> requires less assembly (though probably not fewer code bytes; I didn't check).
> 
> [...]

Applied to kvm-x86 svm, thanks!

[1/8] KVM: SVM: Create a stack frame in __svm_vcpu_run() for unwinding
      https://github.com/kvm-x86/linux/commit/19597a71a0c8
[2/8] KVM: SVM: Wrap __svm_sev_es_vcpu_run() with #ifdef CONFIG_KVM_AMD_SEV
      https://github.com/kvm-x86/linux/commit/7774c8f32e99
[3/8] KVM: SVM: Drop 32-bit "support" from __svm_sev_es_vcpu_run()
      https://github.com/kvm-x86/linux/commit/331282fdb15e
[4/8] KVM: SVM: Clobber RAX instead of RBX when discarding spec_ctrl_intercepted
      https://github.com/kvm-x86/linux/commit/87e8e360a05f
[5/8] KVM: SVM: Save/restore non-volatile GPRs in SEV-ES VMRUN via host save area
      https://github.com/kvm-x86/linux/commit/c92be2fd8edf
[6/8] KVM: SVM: Save/restore args across SEV-ES VMRUN via host save area
      https://github.com/kvm-x86/linux/commit/adac42bf42c1
[7/8] KVM: SVM: Create a stack frame in __svm_sev_es_vcpu_run()
      https://github.com/kvm-x86/linux/commit/4367a75887ec
[8/8] KVM: x86: Stop compiling vmenter.S with OBJECT_FILES_NON_STANDARD
      https://github.com/kvm-x86/linux/commit/27ca867042af

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