From nobody Thu Mar 26 19:03:37 2026 X-Original-To: dev-commits-src-all@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4fhY8V16dMz6WJMk for ; Thu, 26 Mar 2026 19:03:38 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R12" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4fhY8T61wcz3Gmk for ; Thu, 26 Mar 2026 19:03:37 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1774551817; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=cyJLuCeW7+hVYp43RWbhm4+9cAAht2ULt4eK7T1c+lo=; b=Dz1hrcT1rHIq9c5gcKbjIc41LvYnnIn8A7EmGnBIvTFOBOlg3HjR1V8B08alqhklevRIay +kmfdK2Y/eisgNOo2ygRT/cZ8+XWc8Xk2/wqB44XdQenwdcvwU3cn2+kbAOkR+bMpUTdqp iUiZLonKraRxDuAE610+n5EgRb/z41PP3PKy4fiEp3plUa1QqAyqCOBbHoHczuMAscbsuD d+exLz6Y4WnMmdS8KQL30VTVXaknmKaOwjr/S5J24uqy/5svSynb6v8oyLJYGZ7rgRebHd TRGvzY9mrZveV225BSjwkWHchNHsuq4JTwKm2b3x7xLxKa6qiPNjWl9SkQa8vQ== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1774551817; a=rsa-sha256; cv=none; b=lPurQxD6uTj61Ij+hzWmnxHgmpCbQgdG/AdiU9QEzVA49c1nTKbZJQIKCdtezrDUrQjTv9 hdoEJhin/WYbfkp8i9EWZuNvlu2nYubr96Fx64Q8z4+k3CVyLL6eMoV1VGtPC/G5PDgvrC LyLUsdL2DdGT25jxR7Vr5vJqyLoLp46zVEZJI+u95NHYyMbVg+Fc94eUc9s5XnvF9Qdo1C hkGeQDpiiAUqcGZ/I0sE6XC+5Xb3WzeFUkIxAIkOlVYKgVJEAExVbsQ/M2wfwvhHs6YVl5 xHcBx1MepB0jgtEBbQyUPDDi8GmeDGMbyLlTLJ2t+Rq1nkcbxrYlHg3qoKfkZA== ARC-Authentication-Results: i=1; mx1.freebsd.org; none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1774551817; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=cyJLuCeW7+hVYp43RWbhm4+9cAAht2ULt4eK7T1c+lo=; b=xJ3HOGWc4flXVH/LrmdokxXHfSDQx0HkV5BfiBTjS7I8nYgwy47sNaBENMhG7Z3nTQREll NuwXxCI9UUv7wvo9pEF6Mhx3UkfNGA1VATXGWiNo3D0wSQDg+j0bdVj2E2DuVBJUQEZyqv 82FMMPtWBdf9hvU43mXM28eqG6Yc1s40q7eXhWSoRpMd7w1KMGaEEeQ8up7o1fZ1/QvbRQ t6tpbx8la4c/z4H/PtHHkORa53/b3g0acN67j2K2sURp6g/RPlIpertNzeCmxv9F7+qe5h 8DG6QzTYWYWJaTHt9upROLRfA4ZpmwQr5Afogyq/uqjtW5il6hSTyjimTg0bfQ== Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) by mxrelay.nyi.freebsd.org (Postfix) with ESMTP id 4fhY8T5dHRz14c7 for ; Thu, 26 Mar 2026 19:03:37 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from git (uid 1279) (envelope-from git@FreeBSD.org) id 1bba4 by gitrepo.freebsd.org (DragonFly Mail Agent v0.13+ on gitrepo.freebsd.org); Thu, 26 Mar 2026 19:03:37 +0000 To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Cc: Matt Delco From: Alexander Ziaee Subject: git: 7e7d4e711ff9 - main - x86: Handle when MPERF/APERF MSRs aren't writable List-Id: Commit messages for all branches of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-all List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: dev-commits-src-all@freebsd.org Sender: owner-dev-commits-src-all@FreeBSD.org MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: ziaee X-Git-Repository: src X-Git-Refname: refs/heads/main X-Git-Reftype: branch X-Git-Commit: 7e7d4e711ff94d114c93fd522d4125aa9bd9f5cd Auto-Submitted: auto-generated Date: Thu, 26 Mar 2026 19:03:37 +0000 Message-Id: <69c58309.1bba4.70354eb5@gitrepo.freebsd.org> The branch main has been updated by ziaee: URL: https://cgit.FreeBSD.org/src/commit/?id=7e7d4e711ff94d114c93fd522d4125aa9bd9f5cd commit 7e7d4e711ff94d114c93fd522d4125aa9bd9f5cd Author: Matt Delco AuthorDate: 2026-03-26 17:30:31 +0000 Commit: Alexander Ziaee CommitDate: 2026-03-26 19:02:22 +0000 x86: Handle when MPERF/APERF MSRs aren't writable For performance and/or correct reasons some hypervisors allow MPERF/APERF MSRs to be read but not written to. This change modifies the handling of these MSRs to not rely on writes. This patch is part of Google Cloud Engine (GCE) C4-LSSD turnup. Sponsored by: Google Tested by: NetApp (previous) PR: 292808 MFC after: 3 days Co-authored-by: Jim Mattson Reviewed by: jrtc27, imp, kib, markj, olce, obiwac Differential Revision: https://reviews.freebsd.org/D55996 --- sys/x86/x86/cpu_machdep.c | 14 +++++++------- sys/x86/x86/tsc.c | 9 ++++++--- 2 files changed, 13 insertions(+), 10 deletions(-) diff --git a/sys/x86/x86/cpu_machdep.c b/sys/x86/x86/cpu_machdep.c index 775fee97d3cd..422bdf9cfb0d 100644 --- a/sys/x86/x86/cpu_machdep.c +++ b/sys/x86/x86/cpu_machdep.c @@ -423,7 +423,7 @@ int cpu_est_clockrate(int cpu_id, uint64_t *rate) { uint64_t tsc1, tsc2; - uint64_t acnt, mcnt, perf; + uint64_t acnt_start, acnt_end, mcnt_start, mcnt_end, perf; register_t reg; int error = 0; @@ -453,20 +453,20 @@ cpu_est_clockrate(int cpu_id, uint64_t *rate) /* Calibrate by measuring a short delay. */ reg = intr_disable(); if (tsc_is_invariant) { - wrmsr(MSR_MPERF, 0); - wrmsr(MSR_APERF, 0); + mcnt_start = rdmsr(MSR_MPERF); + acnt_start = rdmsr(MSR_APERF); tsc1 = rdtsc(); DELAY(1000); - mcnt = rdmsr(MSR_MPERF); - acnt = rdmsr(MSR_APERF); + mcnt_end = rdmsr(MSR_MPERF); + acnt_end = rdmsr(MSR_APERF); tsc2 = rdtsc(); intr_restore(reg); - if (mcnt == 0) { + if (mcnt_end == mcnt_start) { tsc_perf_stat = 0; error = EOPNOTSUPP; goto err; } - perf = 1000 * acnt / mcnt; + perf = 1000 * (acnt_end - acnt_start) / (mcnt_end - mcnt_start); *rate = (tsc2 - tsc1) * perf; } else { tsc1 = rdtsc(); diff --git a/sys/x86/x86/tsc.c b/sys/x86/x86/tsc.c index 3b873d9dae73..f88ce60c6319 100644 --- a/sys/x86/x86/tsc.c +++ b/sys/x86/x86/tsc.c @@ -433,6 +433,8 @@ probe_tsc_freq_late(void) void start_TSC(void) { + uint64_t mperf, aperf; + if ((cpu_feature & CPUID_TSC) == 0 || tsc_disabled) return; @@ -442,11 +444,12 @@ start_TSC(void) /* * XXX Some emulators expose host CPUID without actual support * for these MSRs. We must test whether they really work. + * They may also be read-only, so test for increment. */ - wrmsr(MSR_MPERF, 0); - wrmsr(MSR_APERF, 0); + mperf = rdmsr(MSR_MPERF); + aperf = rdmsr(MSR_APERF); DELAY(10); - if (rdmsr(MSR_MPERF) > 0 && rdmsr(MSR_APERF) > 0) + if (rdmsr(MSR_MPERF) != mperf && rdmsr(MSR_APERF) != aperf) tsc_perf_stat = 1; }