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ACPI: CPPC: Fix missing PCC check for guaranteed_perf

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commit 6ea3a44cef28add2d93b1ef119d84886cb1e3c9b upstream.

The current implementation overlooks the 'guaranteed_perf'
register in this check.

If the Guaranteed Performance register is located in the PCC
subspace, the function currently attempts to read it without
acquiring the lock and without sending the CMD_READ doorbell
to the firmware. This can result in reading stale data.

Fixes: 29523f0953 ("ACPI / CPPC: Add support for guaranteed performance")
Signed-off-by: Pengjie Zhang <zhangpengjie2@huawei.com>
Cc: 4.20+ <stable@vger.kernel.org> # 4.20+
[ rjw: Subject and changelog edits ]
Link: https://patch.msgid.link/20251210132227.1988380-1-zhangpengjie2@huawei.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Pengjie Zhang
2025-12-10 21:22:27 +08:00
committed by Greg Kroah-Hartman
parent ef0f9059a6
commit a287987af3
1 changed files with 2 additions and 1 deletions
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3
drivers/acpi/cppc_acpi.c
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@@ -1299,7 +1299,8 @@ int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps)
/* Are any of the regs PCC ?*/
if (CPC_IN_PCC(highest_reg) || CPC_IN_PCC(lowest_reg) ||
CPC_IN_PCC(lowest_non_linear_reg) || CPC_IN_PCC(nominal_reg) ||
CPC_IN_PCC(low_freq_reg) || CPC_IN_PCC(nom_freq_reg)) {
CPC_IN_PCC(low_freq_reg) || CPC_IN_PCC(nom_freq_reg) ||
CPC_IN_PCC(guaranteed_reg)) {
if (pcc_ss_id < 0) {
pr_debug("Invalid pcc_ss_id\n");
return -ENODEV;