From: "tip-bot2 for Janakarajan Natarajan" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Janakarajan Natarajan <Janakarajan.Natarajan@amd.com>,
Borislav Petkov <bp@suse.de>,
Frederic Weisbecker <frederic@kernel.org>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
"x86@kernel.org" <x86@kernel.org>,
Zhenzhong Duan <zhenzhong.duan@oracle.com>,
<stable@vger.kernel.org>, Ingo Molnar <mingo@kernel.org>,
Borislav Petkov <bp@alien8.de>,
linux-kernel@vger.kernel.org
Subject: [tip: x86/urgent] x86/asm: Fix MWAITX C-state hint value
Date: Tue, 08 Oct 2019 08:19:32 -0000 [thread overview]
Message-ID: <157052277295.9978.2993482656720588753.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20191007190011.4859-1-Janakarajan.Natarajan@amd.com>
The following commit has been merged into the x86/urgent branch of tip:
Commit-ID: 9b69cab42e5d14b8f0467566e3d97e682365db2d
Gitweb: https://git.kernel.org/tip/9b69cab42e5d14b8f0467566e3d97e682365db2d
Author: Janakarajan Natarajan <Janakarajan.Natarajan@amd.com>
AuthorDate: Mon, 07 Oct 2019 19:00:22
Committer: Borislav Petkov <bp@suse.de>
CommitterDate: Tue, 08 Oct 2019 09:48:09 +02:00
x86/asm: Fix MWAITX C-state hint value
As per "AMD64 Architecture Programmer's Manual Volume 3: General-Purpose
and System Instructions", MWAITX EAX[7:4]+1 specifies the optional hint
of the optimized C-state. For C0 state, EAX[7:4] should be set to 0xf.
Currently, a value of 0xf is set for EAX[3:0] instead of EAX[7:4]. Fix
this by changing MWAITX_DISABLE_CSTATES from 0xf to 0xf0.
This hasn't had any implications so far because setting reserved bits in
EAX is simply ignored by the CPU.
[ bp: Fixup comment in delay_mwaitx() and massage. ]
Signed-off-by: Janakarajan Natarajan <Janakarajan.Natarajan@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "x86@kernel.org" <x86@kernel.org>
Cc: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20191007190011.4859-1-Janakarajan.Natarajan@amd.com
---
arch/x86/include/asm/mwait.h | 2 +-
arch/x86/lib/delay.c | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/mwait.h b/arch/x86/include/asm/mwait.h
index e28f8b7..9d5252c 100644
--- a/arch/x86/include/asm/mwait.h
+++ b/arch/x86/include/asm/mwait.h
@@ -21,7 +21,7 @@
#define MWAIT_ECX_INTERRUPT_BREAK 0x1
#define MWAITX_ECX_TIMER_ENABLE BIT(1)
#define MWAITX_MAX_LOOPS ((u32)-1)
-#define MWAITX_DISABLE_CSTATES 0xf
+#define MWAITX_DISABLE_CSTATES 0xf0
static inline void __monitor(const void *eax, unsigned long ecx,
unsigned long edx)
diff --git a/arch/x86/lib/delay.c b/arch/x86/lib/delay.c
index b7375dc..c126571 100644
--- a/arch/x86/lib/delay.c
+++ b/arch/x86/lib/delay.c
@@ -113,8 +113,8 @@ static void delay_mwaitx(unsigned long __loops)
__monitorx(raw_cpu_ptr(&cpu_tss_rw), 0, 0);
/*
- * AMD, like Intel, supports the EAX hint and EAX=0xf
- * means, do not enter any deep C-state and we use it
+ * AMD, like Intel's MWAIT version, supports the EAX hint and
+ * EAX=0xf0 means, do not enter any deep C-state and we use it
* here in delay() to minimize wakeup latency.
*/
__mwaitx(MWAITX_DISABLE_CSTATES, delay, MWAITX_ECX_TIMER_ENABLE);
next prev parent reply other threads:[~2019-10-08 8:19 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-07 19:00 [PATCH] x86/asm: Fix MWAITX C-state hint value Natarajan, Janakarajan
2019-10-08 8:19 ` [tip: x86/urgent] " tip-bot2 for Janakarajan Natarajan
2019-10-08 8:19 ` tip-bot2 for Janakarajan Natarajan [this message]
2019-10-08 11:33 ` tip-bot2 for Janakarajan Natarajan
2019-10-08 11:33 ` tip-bot2 for Janakarajan Natarajan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=157052277295.9978.2993482656720588753.tip-bot2@tip-bot2 \
--to=tip-bot2@linutronix.de \
--cc=Janakarajan.Natarajan@amd.com \
--cc=bp@alien8.de \
--cc=bp@suse.de \
--cc=frederic@kernel.org \
--cc=gregkh@linuxfoundation.org \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-tip-commits@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=mingo@redhat.com \
--cc=stable@vger.kernel.org \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
--cc=zhenzhong.duan@oracle.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).