From: Yu-cheng Yu <yu-cheng.yu@intel.com>
To: Dave Hansen <dave.hansen@linux.intel.com>
Cc: x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, Andy Lutomirski <luto@kernel.org>,
Borislav Petkov <bp@suse.de>,
Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>,
"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
Fenghua Yu <fenghua.yu@intel.com>
Subject: Re: [PATCH v3 9/9] x86/xsaves: Re-enable XSAVES
Date: Tue, 1 Mar 2016 16:48:34 -0800 [thread overview]
Message-ID: <20160302004834.GA30942@test-lenovo> (raw)
In-Reply-To: <56D637B5.3030907@linux.intel.com>
On Tue, Mar 01, 2016 at 04:45:41PM -0800, Dave Hansen wrote:
> >>> + WARN_ONCE((xfeatures_mask & XFEATURE_MASK_SUPERVISOR),
> >>> + "x86/fpu: XSAVES supervisor states are not yet implemented.\n");
> >>> +
> >>> cr4_set_bits(X86_CR4_OSXSAVE);
> >>> xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask);
> >>> }
> >>
> >> Let's also do a:
> >>
> >> xfeatures_mask &= ~XFEATURE_MASK_SUPERVISOR;
> >>
> >> Otherwise, we have a broken system at the moment.
> >>
> > Currently, if anyone sets any supervisor state in xfeatures_mask, the
> > kernel prints out the warning then goes into a protection fault.
> > That is a very strong indication to the user. Do we want to mute it?
>
> By "goes into a protection fault", do you mean that it doesn't boot?
>
> I'd just rather we put the kernel in a known-safe configuration (masking
> supervisor state out of xfeatures_mask) rather than rely on the general
> protection fault continuing to be generated by whatever is generating it.
>
Ok.
Yu-cheng
next prev parent reply other threads:[~2016-03-02 0:51 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-29 17:41 [PATCH v3 0/9] x86/xsaves: Fix XSAVES known issues Yu-cheng Yu
2016-02-29 17:41 ` [PATCH v3 1/9] x86/xsaves: Define and use user_xstate_size for xstate size in signal context Yu-cheng Yu
2016-02-29 17:42 ` [PATCH v3 2/9] x86/xsaves: Rename xstate_size to kernel_xstate_size to explicitly distinguish xstate size in kernel from user space Yu-cheng Yu
2016-02-29 17:42 ` [PATCH v3 3/9] x86/xsaves: Keep init_fpstate.xsave.header.xfeatures as zero for init optimization Yu-cheng Yu
2016-02-29 17:42 ` [PATCH v3 4/9] x86/xsaves: Introduce a new check that allows correct xstates copy from kernel to user directly Yu-cheng Yu
2016-02-29 17:42 ` [PATCH v3 5/9] x86/xsaves: Align xstate components according to CPUID Yu-cheng Yu
2016-02-29 17:42 ` [PATCH v3 6/9] x86/xsaves: Supervisor state component offset Yu-cheng Yu
2016-02-29 17:42 ` [PATCH v3 7/9] x86/xsaves: Fix PTRACE frames for XSAVES Yu-cheng Yu
2016-02-29 17:42 ` [PATCH v3 8/9] x86/xsaves: Fix XSTATE component offset print out Yu-cheng Yu
2016-02-29 17:42 ` [PATCH v3 9/9] x86/xsaves: Re-enable XSAVES Yu-cheng Yu
2016-03-01 23:56 ` Dave Hansen
2016-03-02 0:34 ` Yu-cheng Yu
2016-03-02 0:45 ` Dave Hansen
2016-03-02 0:48 ` Yu-cheng Yu [this message]
2016-03-02 0:53 ` H. Peter Anvin
2016-03-02 0:58 ` Yu-cheng Yu
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