linux-kernel - Re: [CFT PATCH 2/2] KVM: x86: support XSAVES usage in the host

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Message-ID: <20141124021009.GB27849@kernel>
Date:	Mon, 24 Nov 2014 10:10:09 +0800
From:	Wanpeng Li <wanpeng.li@...ux.intel.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
Cc:	linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
	Fenghua Yu <fenghua.yu@...el.com>, stable@...r.kernel.org,
	Nadav Amit <namit@...technion.ac.il>,
	Andy Lutomirski <luto@...capital.net>
Subject: Re: [CFT PATCH 2/2] KVM: x86: support XSAVES usage in the host

Hi Paolo,
On Fri, Nov 21, 2014 at 07:31:18PM +0100, Paolo Bonzini wrote:
[...]
>+		u64 feature = valid & -valid;
>+		int index = fls64(feature) - 1;
>+		void *src = get_xsave_addr(xsave, feature);
>+
>+	        if (src) {
>+			u32 size, offset, ecx, edx;
>+			cpuid_count(XSTATE_CPUID, index,
>+				    &size, &offset, &ecx, &edx);
>+	                memcpy(dest + offset, src, size);

The offset you get is still for compact format, so you almost convert compat 
format to compat format instead of convert compact format to standard format. 
In addition, I think convert standard format to compact format should be 
implemented in put path.

Regards,
Wanpeng Li 

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