From: "Jan Beulich" <JBeulich@suse.com>
To: Shuai Ruan <shuai.ruan@linux.intel.com>
Cc: andrew.cooper3@citrix.com, keir@xen.org, xen-devel@lists.xen.org
Subject: Re: [PATCH V7 3/3] x86/xsaves: ebx may return wrong value using CPUID eax=0xdh, ecx =1
Date: Tue, 05 Apr 2016 02:31:40 -0600 [thread overview]
Message-ID: <5703940C02000078000E3105@prv-mh.provo.novell.com> (raw)
In-Reply-To: <1459414657-7558-4-git-send-email-shuai.ruan@linux.intel.com>
>>> On 31.03.16 at 10:57, <shuai.ruan@linux.intel.com> wrote:
> Refer to SDM 13.4.3 Extended Region of an XSAVE Area. The value return
No section numbers please - they tend to change.
> by ecx[1] with cpuid function 0xdh and sub-fucntion i (i>1) indicates
Either "0xd" or "0dh". And "function".
> --- a/xen/arch/x86/traps.c
> +++ b/xen/arch/x86/traps.c
> @@ -1020,6 +1020,18 @@ void pv_cpuid(struct cpu_user_regs *regs)
> a &= (boot_cpu_data.x86_capability[cpufeat_word(X86_FEATURE_XSAVEOPT)] &
> ~cpufeat_mask(X86_FEATURE_XSAVES));
> b = c = d = 0;
> + if ( cpu_has_xsavec )
> + {
> + b = XSTATE_AREA_MIN_SIZE;
Is this really correct namely when curr->arch.xcr0 == 0? If not, the
if() below should perhaps be combined with the if() above (and then
the same would apply to hvm_cpuid()).
> + if ( curr->arch.xcr0 )
> + for( subleaf = 2; subleaf < 63; subleaf++ )
> + if ( (1ULL << subleaf) & curr->arch.xcr0 )
The first if() is redundant with this second one. If you really
mean to avoid the loop, then please also only check bits
2..62 in the first if().
Jan
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next prev parent reply other threads:[~2016-04-05 8:31 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-31 8:57 [PATCH V7 0/3] xsaves bug fix Shuai Ruan
2016-03-31 8:57 ` [PATCH V7 1/3] x86/xsaves: fix overwriting between non-lazy/lazy xsaves Shuai Ruan
2016-04-04 15:51 ` Jan Beulich
2016-04-05 5:30 ` Shuai Ruan
[not found] ` <20160405053023.GA16876@shuai.ruan@linux.intel.com>
2016-04-05 7:17 ` Jan Beulich
2016-04-05 7:29 ` Shuai Ruan
2016-04-25 6:51 ` Jan Beulich
2016-04-29 1:36 ` Shuai Ruan
[not found] ` <20160429013616.GB4359@shuai.ruan@linux.intel.com>
2016-04-29 7:05 ` Jan Beulich
2016-03-31 8:57 ` [PATCH V7 2/3] x86/xsaves: fix two remained issues Shuai Ruan
2016-04-04 16:03 ` Jan Beulich
2016-03-31 8:57 ` [PATCH V7 3/3] x86/xsaves: ebx may return wrong value using CPUID eax=0xdh, ecx =1 Shuai Ruan
2016-04-05 8:31 ` Jan Beulich [this message]
2016-04-06 7:01 ` Shuai Ruan
[not found] ` <20160406070034.GA26357@shuai.ruan@linux.intel.com>
2016-04-07 0:29 ` Jan Beulich
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