From: Vanshidhar Konda <vanshikonda@os.amperecomputing.com>
To: Jarred White <jarredwhite@linux.microsoft.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>,
Len Brown <lenb@kernel.org>,
Easwar Hariharan <eahariha@linux.microsoft.com>,
"open list:ACPI" <linux-acpi@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>,
stable@vger.kernel.org
Subject: Re: [PATCH] ACPI: CPPC: Fix bit_offset shift in MASK_VAL macro
Date: Wed, 17 Apr 2024 10:36:59 -0700 [thread overview]
Message-ID: <soawdod6cpcc73wrc35bvnah5toubf2cv4x7c3e6p53xtvllrs@6dtpn2v5t3di> (raw)
In-Reply-To: <20240409052310.3162495-1-jarredwhite@linux.microsoft.com>
Looks good to me.
Reviewed-by: Vanshidhar Konda <vanshikonda@os.amperecomputing.com>
On Mon, Apr 08, 2024 at 10:23:09PM -0700, Jarred White wrote:
>Commit 2f4a4d63a193 ("ACPI: CPPC: Use access_width over bit_width for
>system memory accesses") neglected to properly wrap the bit_offset shift
>when it comes to applying the mask. This may cause incorrect values to be
>read and may cause the cpufreq module not be loaded.
>
>[ 11.059751] cpu_capacity: CPU0 missing/invalid highest performance.
>[ 11.066005] cpu_capacity: partial information: fallback to 1024 for all CPUs
>
>Also, corrected the bitmask generation in GENMASK (extra bit being added).
>
>Fixes: 2f4a4d63a193 ("ACPI: CPPC: Use access_width over bit_width for system memory accesses")
>Signed-off-by: Jarred White <jarredwhite@linux.microsoft.com>
>CC: Vanshidhar Konda <vanshikonda@os.amperecomputing.com>
>CC: stable@vger.kernel.org #5.15+
>---
> drivers/acpi/cppc_acpi.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
>diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
>index 4bfbe55553f4..00a30ca35e78 100644
>--- a/drivers/acpi/cppc_acpi.c
>+++ b/drivers/acpi/cppc_acpi.c
>@@ -170,8 +170,8 @@ show_cppc_data(cppc_get_perf_ctrs, cppc_perf_fb_ctrs, wraparound_time);
> #define GET_BIT_WIDTH(reg) ((reg)->access_width ? (8 << ((reg)->access_width - 1)) : (reg)->bit_width)
>
> /* Shift and apply the mask for CPC reads/writes */
>-#define MASK_VAL(reg, val) ((val) >> ((reg)->bit_offset & \
>- GENMASK(((reg)->bit_width), 0)))
>+#define MASK_VAL(reg, val) (((val) >> (reg)->bit_offset) & \
>+ GENMASK(((reg)->bit_width) - 1, 0))
>
> static ssize_t show_feedback_ctrs(struct kobject *kobj,
> struct kobj_attribute *attr, char *buf)
>--
>2.33.8
>
next prev parent reply other threads:[~2024-04-17 17:37 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-09 5:23 [PATCH] ACPI: CPPC: Fix bit_offset shift in MASK_VAL macro Jarred White
2024-04-16 17:24 ` Jarred White
2024-04-17 17:36 ` Vanshidhar Konda [this message]
2024-04-22 16:43 ` Rafael J. Wysocki
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=soawdod6cpcc73wrc35bvnah5toubf2cv4x7c3e6p53xtvllrs@6dtpn2v5t3di \
--to=vanshikonda@os.amperecomputing.com \
--cc=eahariha@linux.microsoft.com \
--cc=jarredwhite@linux.microsoft.com \
--cc=lenb@kernel.org \
--cc=linux-acpi@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=rafael@kernel.org \
--cc=stable@vger.kernel.org \
/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 read-only IMAP folder(s) and NNTP newsgroup(s).