linux-kernel - [PATCH 4.9 152/223] perf/x86/amd/uncore: Get correct number of cores sharing last level cache

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20190802092248.283719085@linuxfoundation.org>
Date:   Fri,  2 Aug 2019 11:36:17 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Janakarajan Natarajan <Janakarajan.Natarajan@....com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Borislav Petkov <bp@...e.de>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>
Subject: [PATCH 4.9 152/223] perf/x86/amd/uncore: Get correct number of cores sharing last level cache

In Family 17h, the number of cores sharing a cache level is obtained
from the Cache Properties CPUID leaf (0x8000001d) by passing in the
cache level in ECX. In prior families, a cache level of 2 was used to
determine this information.

To get the right information, irrespective of Family, iterate over
the cache levels using CPUID 0x8000001d. The last level cache is the
last value to return a non-zero value in EAX.

Signed-off-by: Janakarajan Natarajan <Janakarajan.Natarajan@....com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Borislav Petkov <bp@...e.de>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/5ab569025b39cdfaeca55b571d78c0fc800bdb69.1497452002.git.Janakarajan.Natarajan@amd.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/events/amd/uncore.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/arch/x86/events/amd/uncore.c b/arch/x86/events/amd/uncore.c
index 094973313037..10f023799f11 100644
--- a/arch/x86/events/amd/uncore.c
+++ b/arch/x86/events/amd/uncore.c
@@ -378,11 +378,24 @@ static int amd_uncore_cpu_starting(unsigned int cpu)
 
 	if (amd_uncore_llc) {
 		unsigned int apicid = cpu_data(cpu).apicid;
-		unsigned int nshared;
+		unsigned int nshared, subleaf, prev_eax = 0;
 
 		uncore = *per_cpu_ptr(amd_uncore_llc, cpu);
-		cpuid_count(0x8000001d, 2, &eax, &ebx, &ecx, &edx);
-		nshared = ((eax >> 14) & 0xfff) + 1;
+		/*
+		 * Iterate over Cache Topology Definition leaves until no
+		 * more cache descriptions are available.
+		 */
+		for (subleaf = 0; subleaf < 5; subleaf++) {
+			cpuid_count(0x8000001d, subleaf, &eax, &ebx, &ecx, &edx);
+
+			/* EAX[0:4] gives type of cache */
+			if (!(eax & 0x1f))
+				break;
+
+			prev_eax = eax;
+		}
+		nshared = ((prev_eax >> 14) & 0xfff) + 1;
+
 		uncore->id = apicid - (apicid % nshared);
 
 		uncore = amd_uncore_find_online_sibling(uncore, amd_uncore_llc);
-- 
2.20.1