From: Rik van Riel <riel@redhat.com>
To: Borislav Petkov <bp@suse.de>
Cc: mingo@kernel.org, linux-kernel@vger.kernel.org, luto@kernel.org,
dave.hansen@linux.intel.com, yu-cheng.yu@intel.com,
hpa@zytor.com
Subject: Re: [PATCH v2] x86/fpu: copy MXCSR & MXCSR_FLAGS with SSE/YMM state
Date: Thu, 09 Feb 2017 19:51:29 -0500 [thread overview]
Message-ID: <1486687889.2096.29.camel@redhat.com> (raw)
In-Reply-To: <20170210000224.qgwwyozscwjegpqm@pd.tnic>
On Fri, 2017-02-10 at 01:02 +0100, Borislav Petkov wrote:
> On Thu, Feb 09, 2017 at 06:43:47PM -0500, Rik van Riel wrote:
> > On Skylake CPUs I noticed that XRSTOR is unable to deal with xsave
> > areas
> > created by copyout_from_xsaves if the xstate has only SSE/YMM
> > state, but
> > no FP state. That is, xfeatures had XFEATURE_MASK_SSE set, but not
> > XFEATURE_MASK_FP.
> >
> > The reason is that part of the SSE/YMM state lives in the MXCSR and
> > MXCSR_FLAGS fields of the FP area.
> >
> > Ensure that whenever we copy SSE or YMM state around, the MXCSR and
> > MXCSR_FLAGS fields are also copied around.
> >
> > Signed-off-by: Rik van Riel <riel@redhat.com>
> > ---
> > arch/x86/kernel/fpu/xstate.c | 44
> > ++++++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 44 insertions(+)
>
> ...
>
> > @@ -987,6 +1004,13 @@ int copy_xstate_to_kernel(void *kbuf, struct
> > xregs_state *xsave, unsigned int of
> >
> > }
> >
> > + if (xfeatures_need_mxcsr_copy(header.xfeatures)) {
> > + offset = offsetof(struct fxregs_state, mxcsr);
> > + size = sizeof(u64); // copy mxcsr & mxcsr_flags
>
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> We don't do // comments, do we?
>
> And side-line comments are always impairing the readability of the
> code
> unless it is a struct's members or asm or so ...
Good point. OTOH, I don't really want to add an extra line
to each of these blocks of code, either...
Ingo, how would you like me to do these comments?
Or should I have a magic #define with comment somewhere,
like this?
/* Copy both mxcsr & mxcsr_flags */
#define MXCSR_AND_FLAGS_SIZE sizeof(u64)
next prev parent reply other threads:[~2017-02-10 1:18 UTC|newest]
Thread overview: 94+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-09 23:43 [PATCH v2] x86/fpu: copy MXCSR & MXCSR_FLAGS with SSE/YMM state Rik van Riel
2017-02-10 0:02 ` Borislav Petkov
2017-02-10 0:51 ` Rik van Riel [this message]
2017-02-10 8:00 ` Ingo Molnar
2017-02-10 13:54 ` [PATCH v3] " Rik van Riel
2017-02-11 10:02 ` Ingo Molnar
2017-04-24 20:54 ` [tip:perf/core] x86/fpu: Add FPU state copying quirk to handle XRSTOR failure on Intel Skylake CPUs tip-bot for Rik van Riel
2017-02-10 0:45 ` [PATCH v2] x86/fpu: copy MXCSR & MXCSR_FLAGS with SSE/YMM state Yu-cheng Yu
2017-02-10 1:00 ` Rik van Riel
2017-02-10 17:18 ` Yu-cheng Yu
2017-03-06 0:45 [tip:WIP.x86/fpu 31/31] arch/x86/kernel/fpu/xstate.c:931:9-10: WARNING: return of 0/1 in function 'xfeatures_mxcsr_quirk' with return type bool kbuild test robot
2017-03-06 0:45 ` [PATCH] x86/fpu: fix boolreturn.cocci warnings kbuild test robot
2017-03-07 7:23 ` Ingo Molnar
2017-03-07 8:33 ` Thomas Gleixner
2017-03-07 9:01 ` Ingo Molnar
2017-03-07 12:01 ` Joe Perches
2017-04-24 20:54 ` [tip:perf/core] x86/fpu: Fix " tip-bot for kbuild test robot
2017-03-29 6:26 [PATCH] x86/fpu: Turn WARN_ON in context switch into WARN_ON_FPU Andi Kleen
2017-04-24 21:00 ` [tip:perf/core] x86/fpu: Turn WARN_ON() in context switch into WARN_ON_FPU() tip-bot for Andi Kleen
2017-09-22 17:41 [PATCH v4 0/3] x86/fpu: prevent leaking FPU registers via invalid FPU state Eric Biggers
2017-09-22 17:41 ` [PATCH v4 1/3] x86/fpu: don't let userspace set bogus xcomp_bv Eric Biggers
2017-09-22 17:41 ` [PATCH v4 2/3] x86/fpu: tighten validation of user-supplied xstate_header Eric Biggers
2017-09-22 17:41 ` [PATCH v4 3/3] x86/fpu: reinitialize FPU registers if restoring FPU state fails Eric Biggers
2017-09-23 9:09 ` [PATCH v4 0/3] x86/fpu: prevent leaking FPU registers via invalid FPU state Ingo Molnar
2017-09-23 12:59 [PATCH 00/33] x86 FPU fixes and cleanups for v4.14 Ingo Molnar
2017-09-23 12:59 ` [PATCH 01/33] x86/fpu: Rename copyin_to_xsaves()/copyout_from_xsaves() to copy_user_to_xstate()/copy_xstate_to_user() Ingo Molnar
2017-09-26 8:21 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 12:59 ` [PATCH 02/33] x86/fpu: Split copy_xstate_to_user() into copy_xstate_to_kernel() & copy_xstate_to_user() Ingo Molnar
2017-09-26 8:22 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 12:59 ` [PATCH 03/33] x86/fpu: Remove 'ubuf' parameter from the copy_xstate_to_kernel() APIs Ingo Molnar
2017-09-26 8:22 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 12:59 ` [PATCH 04/33] x86/fpu: Remove 'kbuf' parameter from the copy_xstate_to_user() APIs Ingo Molnar
2017-09-26 8:23 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 12:59 ` [PATCH 05/33] x86/fpu: Clean up parameter order in the copy_xstate_to_*() APIs Ingo Molnar
2017-09-26 8:23 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 12:59 ` [PATCH 06/33] x86/fpu: Clean up the parameter definitions of copy_xstate_to_*() Ingo Molnar
2017-09-26 8:23 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 12:59 ` [PATCH 07/33] x86/fpu: Remove the 'start_pos' parameter from the __copy_xstate_to_*() functions Ingo Molnar
2017-09-26 8:24 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 12:59 ` [PATCH 08/33] x86/fpu: Clarify parameter names in the copy_xstate_to_*() methods Ingo Molnar
2017-09-25 19:56 ` Thomas Gleixner
2017-09-25 20:01 ` Thomas Gleixner
2017-09-26 8:24 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 12:59 ` [PATCH 09/33] x86/fpu: Change 'size_total' parameter to unsigned and standardize the size checks in copy_xstate_to_*() Ingo Molnar
2017-09-26 8:25 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 12:59 ` [PATCH 10/33] x86/fpu: Simplify __copy_xstate_to_kernel() return values Ingo Molnar
2017-09-26 8:25 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 12:59 ` [PATCH 11/33] x86/fpu: Split copy_user_to_xstate() into copy_kernel_to_xstate() & copy_user_to_xstate() Ingo Molnar
2017-09-26 8:25 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 12:59 ` [PATCH 12/33] x86/fpu: Remove 'ubuf' parameter from the copy_kernel_to_xstate() API Ingo Molnar
2017-09-26 8:26 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 12:59 ` [PATCH 13/33] x86/fpu: Remove 'kbuf' parameter from the copy_user_to_xstate() API Ingo Molnar
2017-09-26 8:26 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 12:59 ` [PATCH 14/33] x86/fpu: Flip the parameter order in copy_*_to_xstate() Ingo Molnar
2017-09-26 8:27 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 12:59 ` [PATCH 15/33] x86/fpu: Simplify fpu->fpregs_active use Ingo Molnar
2017-09-26 8:27 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 12:59 ` [PATCH 16/33] x86/fpu: Make the fpu state change in fpu__clear() scheduler-atomic Ingo Molnar
2017-09-26 8:27 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 13:00 ` [PATCH 17/33] x86/fpu: Split the state handling in fpu__drop() Ingo Molnar
2017-09-26 8:28 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 13:00 ` [PATCH 18/33] x86/fpu: Change fpu->fpregs_active users to fpu->fpstate_active Ingo Molnar
2017-09-26 8:28 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 13:00 ` [PATCH 19/33] x86/fpu: Decouple fpregs_activate()/fpregs_deactivate() from fpu->fpregs_active Ingo Molnar
2017-09-26 8:28 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 13:00 ` [PATCH 20/33] x86/fpu: Remove struct fpu::fpregs_active Ingo Molnar
2017-09-26 8:29 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 13:00 ` [PATCH 21/33] x86/fpu: Add FPU state copying quirk to handle XRSTOR failure on Intel Skylake CPUs Ingo Molnar
2017-09-26 8:29 ` [tip:x86/fpu] " tip-bot for Rik van Riel
2017-09-23 13:00 ` [PATCH 22/33] x86/fpu: Fix boolreturn.cocci warnings Ingo Molnar
2017-09-26 8:30 ` [tip:x86/fpu] " tip-bot for kbuild test robot
2017-09-23 13:00 ` [PATCH 23/33] x86/fpu: Turn WARN_ON() in context switch into WARN_ON_FPU() Ingo Molnar
2017-09-26 8:30 ` [tip:x86/fpu] " tip-bot for Andi Kleen
2017-09-23 13:00 ` [PATCH 24/33] x86/fpu: Don't let userspace set bogus xcomp_bv Ingo Molnar
2017-09-26 8:30 ` [tip:x86/fpu] " tip-bot for Eric Biggers
2017-09-23 13:00 ` [PATCH 25/33] x86/fpu: Tighten validation of user-supplied xstate_header Ingo Molnar
2017-09-23 13:00 ` [PATCH 26/33] x86/fpu: Reinitialize FPU registers if restoring FPU state fails Ingo Molnar
2017-09-26 8:31 ` [tip:x86/fpu] " tip-bot for Eric Biggers
2017-09-23 13:00 ` [PATCH 27/33] x86/fpu: Simplify fpu__activate_fpstate_read() Ingo Molnar
2017-09-26 8:31 ` [tip:x86/fpu] x86/fpu: Fix fpu__activate_fpstate_read() and update comments tip-bot for Ingo Molnar
2017-09-23 13:00 ` [PATCH 28/33] x86/fpu: Remove fpu__current_fpstate_write_begin/end() Ingo Molnar
2017-09-26 8:32 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 13:00 ` [PATCH 29/33] x86/fpu: Rename fpu::fpstate_active to fpu::initialized Ingo Molnar
2017-09-26 8:32 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 13:00 ` [PATCH 30/33] x86/fpu: Fix stale comments about lazy FPU logic Ingo Molnar
2017-09-26 8:32 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 13:00 ` [PATCH 31/33] x86/fpu: Simplify and speed up fpu__copy() Ingo Molnar
2017-09-26 8:33 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 13:00 ` [PATCH 32/33] x86/fpu: Rename fpu__activate_curr() to fpu__initialize() Ingo Molnar
2017-09-26 8:33 ` [tip:x86/fpu] " tip-bot for Ingo Molnar
2017-09-23 13:00 ` [PATCH 33/33] x86/fpu: Rename fpu__activate_fpstate_read/write() to fpu__read/write() Ingo Molnar
2017-09-23 13:02 ` [PATCH 00/33] x86 FPU fixes and cleanups for v4.14 Ingo Molnar
2017-09-23 15:03 ` Juergen Gross
2017-09-23 23:27 ` Ingo Molnar
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