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Message-ID: <5626D97C.1060609@gmail.com> Date: Wed, 21 Oct 2015 02:17:00 +0200 From: John Doe <securef33d@...il.com> To: Boris Ostrovsky <boris.ostrovsky@...cle.com>, Jan Beulich <JBeulich@...e.com> Cc: Ingo Molnar <mingo@...nel.org>, x86@...nel.org, xen-devel@...ts.xen.org, linux-kernel@...r.kernel.org Subject: Re: [Xen-devel] PROBLEM: kernel panic xsave_init On 20/10/2015 16:27, Boris Ostrovsky wrote: > On 10/20/2015 09:43 AM, Jan Beulich wrote: >>>>> On 20.10.15 at 15:22, <boris.ostrovsky@...cle.com> wrote: >>> The reason I think its this commit is that RAX, RDX and RCX look very >>> much like arguments to xsetbv (which xstate_enable_boot_cpu() executes) >>> and RAX value is 0x1f, which has two new bits that this commit defined. >> That would be the two MPX related bits, yet us (luckily) white listing >> leaf 7 in pv_cpuid(), it is quite easy to validate that we don't expose >> this feature to PV(H) guests. > > Oh, so something like > > cpuid=['0x7:ebx=xxxxxxxxxxxxxxxxx0xxxxxxxxxxxxxx'] > > (bit 14 as zero) for John to try then. > > > -boris > >> Sadly the story is different for HVM >> guests (where the leaf handling uses black listing), but the register >> dump here clearly points to a PV guest (or Dom0). >> >> Jan >> > Jan the dump is taken from serial connection to Dom0, it does crash during boot. I just tried with xen 4.6.0 and it booted properly without xsave=0. Running gdb against /proc/kcore, with a x/10x 0xffffffff81d58fad i just get null bytes, with both xen4.4.3 (xsave=0) and 4.6.0. Tomorrow i will send you the gdb output and i will try to run it during the boot process. J. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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