linux-kernel - [tip:x86/fpu] x86/fpu: Update comment for __raw_xsave

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Message-ID: <tip-2f2fcc40a961ed04f0e130803fbaa868c2899310@git.kernel.org>
Date:   Mon, 3 Dec 2018 13:03:48 -0800
From:   tip-bot for Sebastian Andrzej Siewior <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     luto@...nel.org, riel@...riel.com, bigeasy@...utronix.de,
        hpa@...or.com, rkrcmar@...hat.com, bp@...e.de, pbonzini@...hat.com,
        tglx@...utronix.de, mingo@...hat.com, mingo@...nel.org,
        kvm@...r.kernel.org, x86@...nel.org, Jason@...c4.com,
        linux-kernel@...r.kernel.org, dave.hansen@...ux.intel.com
Subject: [tip:x86/fpu] x86/fpu: Update comment for __raw_xsave_addr()

Commit-ID:  2f2fcc40a961ed04f0e130803fbaa868c2899310
Gitweb:     https://git.kernel.org/tip/2f2fcc40a961ed04f0e130803fbaa868c2899310
Author:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
AuthorDate: Wed, 28 Nov 2018 23:20:12 +0100
Committer:  Borislav Petkov <bp@...e.de>
CommitDate: Mon, 3 Dec 2018 19:27:14 +0100

x86/fpu: Update comment for __raw_xsave_addr()

The comment above __raw_xsave_addr() claims that the function does not
work for compacted buffers and was introduced in:

  b8b9b6ba9dec3 ("x86/fpu: Allow setting of XSAVE state")

In this commit, the function was factored out of get_xsave_addr() and
this function claims that it works with "standard format or compacted
format of xsave area". It accesses the "xstate_comp_offsets" variable
for the actual offset and it was introduced in commit

  7496d6458fe32 ("Define kernel API to get address of each state in xsave area")

Based on the code (back then and now):
- xstate_offsets holds the standard offset.
- if compacted mode is not supported then xstate_comp_offsets gets the
  xstate_offsets copied.
- if compacted mode is supported then xstate_comp_offsets will hold the
  offset for the compacted buffer.

Based on that the function works for compacted buffers as long as the
CPU supports it and this what we care about.

Remove the "Note:" which is not accurate.

Suggested-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Rik van Riel <riel@...riel.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: "Jason A. Donenfeld" <Jason@...c4.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Radim Krčmář <rkrcmar@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: kvm ML <kvm@...r.kernel.org>
Cc: x86-ml <x86@...nel.org>
Link: https://lkml.kernel.org/r/20181128222035.2996-7-bigeasy@linutronix.de
---
 arch/x86/kernel/fpu/xstate.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 69d5740ed254..359564beab5c 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -808,8 +808,6 @@ void fpu__resume_cpu(void)
  * Given an xstate feature mask, calculate where in the xsave
  * buffer the state is.  Callers should ensure that the buffer
  * is valid.
- *
- * Note: does not work for compacted buffers.
  */
 void *__raw_xsave_addr(struct xregs_state *xsave, int xstate_feature_mask)
 {