linux-kernel - Re: [PATCH 1/3] KVM: SVM: Force sev_es_host_save

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Message-ID: <20240618101743.GCZnFexxIaHkDsv_kG@fat_crate.local>
Date: Tue, 18 Jun 2024 12:17:43 +0200
From: Borislav Petkov <bp@...en8.de>
To: Sean Christopherson <seanjc@...gle.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] KVM: SVM: Force sev_es_host_save_area() to be
 inlined (for noinstr usage)

On Mon, Jun 17, 2024 at 02:04:30PM -0700, Sean Christopherson wrote:
> Force sev_es_host_save_area() to be always inlined, as it's used in the
> low level VM-Enter/VM-Exit path, which is non-instrumentable.
> 
>   vmlinux.o: warning: objtool: svm_vcpu_enter_exit+0xb0: call to
>     sev_es_host_save_area() leaves .noinstr.text section
>   vmlinux.o: warning: objtool: svm_vcpu_enter_exit+0xbf: call to
>     sev_es_host_save_area.isra.0() leaves .noinstr.text section
> 
> Fixes: c92be2fd8edf ("KVM: SVM: Save/restore non-volatile GPRs in SEV-ES VMRUN via host save area")
> Reported-by: Borislav Petkov <bp@...en8.de>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
>  arch/x86/kvm/svm/svm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 9ac6fca50cf3..0a36c82b316f 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -1504,7 +1504,7 @@ static void svm_vcpu_free(struct kvm_vcpu *vcpu)
>  	__free_pages(virt_to_page(svm->msrpm), get_order(MSRPM_SIZE));
>  }
>  
> -static struct sev_es_save_area *sev_es_host_save_area(struct svm_cpu_data *sd)
> +static __always_inline struct sev_es_save_area *sev_es_host_save_area(struct svm_cpu_data *sd)
>  {
>  	return page_address(sd->save_area) + 0x400;
>  }
> -- 

Tested-by: Borislav Petkov (AMD) <bp@...en8.de>

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette