linux-kernel - Re: [PART1 RFC 4/9] KVM: x86: Detect and Initialize AVIC support

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Date:	Fri, 12 Feb 2016 15:13:37 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Cc:	joro@...tes.org, alex.williamson@...hat.com, gleb@...nel.org,
	pbonzini@...hat.com, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, wei@...hat.com,
	sherry.hurwitz@....com
Subject: Re: [PART1 RFC 4/9] KVM: x86: Detect and Initialize AVIC support

On Fri, Feb 12, 2016 at 08:59:29PM +0700, Suravee Suthikulpanit wrote:
> From: Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>
> 
> This patch introduces AVIC-related data structure, and AVIC
> intitialization code.
> 
> There are three main data structures for AVIC:
>     * Virtual APIC (vAPIC) backing page (per-VCPU)
>     * Physical APIC ID table (per-VM)
>     * Logical APIC ID table (per-VM)
> 
> In order to accommodate the new per-VM tables, we introduce
> a new per-VM arch-specific void pointer, struct kvm_arch.arch_data.
> This will point to the newly introduced struct svm_vm_data.
> 
> This patch also introduces code to detect the new new SVM feature CPUID
> Fn8000_000A_EDX[13], which identifies support for AMD Advance Virtual
> Interrupt Controller (AVIC).
> 
> Currently, AVIC is disabled by default. Users can manually
> enable AVIC via kernel boot option kvm-amd.avic=1 or during
> kvm-amd module loading with parameter avic=1.
> 
> Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>
> ---
>  arch/x86/include/asm/cpufeature.h |   1 +
>  arch/x86/include/asm/kvm_host.h   |   2 +
>  arch/x86/kernel/cpu/scattered.c   |   1 +
>  arch/x86/kvm/svm.c                | 404 +++++++++++++++++++++++++++++++++++++-
>  4 files changed, 407 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
> index 7ad8c94..ee85900 100644
> --- a/arch/x86/include/asm/cpufeature.h
> +++ b/arch/x86/include/asm/cpufeature.h
> @@ -203,6 +203,7 @@
>  
>  #define X86_FEATURE_VMMCALL     ( 8*32+15) /* Prefer vmmcall to vmcall */
>  #define X86_FEATURE_XENPV       ( 8*32+16) /* "" Xen paravirtual guest */
> +#define X86_FEATURE_AVIC        ( 8*32+17) /* AMD Virtual Interrupt Controller support */
>  
>  
>  /* Intel-defined CPU features, CPUID level 0x00000007:0 (ebx), word 9 */
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 44adbb8..7b78328 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -754,6 +754,8 @@ struct kvm_arch {
>  
>  	bool irqchip_split;
>  	u8 nr_reserved_ioapic_pins;
> +
> +	void *arch_data;
>  };
>  
>  struct kvm_vm_stat {
> diff --git a/arch/x86/kernel/cpu/scattered.c b/arch/x86/kernel/cpu/scattered.c
> index 8cb57df..88cfbe7 100644
> --- a/arch/x86/kernel/cpu/scattered.c
> +++ b/arch/x86/kernel/cpu/scattered.c
> @@ -37,6 +37,7 @@ void init_scattered_cpuid_features(struct cpuinfo_x86 *c)
>  		{ X86_FEATURE_HW_PSTATE,	CR_EDX, 7, 0x80000007, 0 },
>  		{ X86_FEATURE_CPB,		CR_EDX, 9, 0x80000007, 0 },
>  		{ X86_FEATURE_PROC_FEEDBACK,	CR_EDX,11, 0x80000007, 0 },
> +		{ X86_FEATURE_AVIC,		CR_EDX,13, 0x8000000a, 0 },
>  		{ 0, 0, 0, 0, 0 }
>  	};

You need to check tip/master when/before/after touching arch/x86/:

a1ff57260818 ("x86/cpufeature: Add AMD AVIC bit")

-- 
Regards/Gruss,
    Boris.

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