From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AE1FB3D330B for ; Thu, 28 May 2026 11:47:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779968860; cv=none; b=sDm9D04x6EmBxnphghJJOveZRudVVbH9C2RaA7ym9cWCd4J0jasfUnXUPS346FyZsmC14b/mhotNs9bcKO+AnkZMqA5xLx59ytYZFke2gdqTaG9QqLf1Pgo0oABvsLAAMhyhWJgrdvPAGzLRSaytjKXSDz5lE5GgB0JkwLP4dP0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779968860; c=relaxed/simple; bh=9tAqu56CMprg+muwuUT1jkjfYAZSGlh9eXgJYMyeQd0=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=rPsCtAJ7NadJ1KyQXZZMSkhbIyrPcfoYtI+Gn3G7LZxxLrorI9VIt/207YKcrWkXzpC1tfOIk071j4WVAeCDC+ZpyQ0+Lvf9aq6o3eBY4G6gA39/BqdxGFmMcvvf3CFfq9qBx27CVeyFJm4HlyJSzp5wXqzS/YzU4BVYvFAzJkU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=rzH/r7jb; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="rzH/r7jb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0B30C1F000E9; Thu, 28 May 2026 11:47:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1779968858; bh=D8aOoirjNZVzvbncmpFZHRPbIcDZJKBD4CpE1Shn3f0=; h=Subject:To:Cc:From:Date; b=rzH/r7jbmf53TxPAJoNKLDpEYsoQabFv4HRINt++mJ+FEgS/7nNMl5PFQ/vTXj8To JEFT6GRK4nhcywrsf1oOKHWBJdUFCyl2JNKDvXhXae5IAParONjVZZffbSQASaq/KP zuK8ZzbgQYoJXRGdpJ/MDLVbPrxXnWK4ttLxohQ4= Subject: FAILED: patch "[PATCH] s390/pai: Fix missing PAI counter increments under heavy load" failed to apply to 6.18-stable tree To: tmricht@linux.ibm.com,agordeev@linux.ibm.com,sumanthk@linux.ibm.com Cc: From: Date: Thu, 28 May 2026 13:46:45 +0200 Message-ID: <2026052845-oozy-cargo-663a@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.18-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y git checkout FETCH_HEAD git cherry-pick -x 99269799bf2448aebccee164df56c22a7b85b02c # git commit -s git send-email --to '' --in-reply-to '2026052845-oozy-cargo-663a@gregkh' --subject-prefix 'PATCH 6.18.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 99269799bf2448aebccee164df56c22a7b85b02c Mon Sep 17 00:00:00 2001 From: Thomas Richter Date: Tue, 5 May 2026 12:34:33 +0200 Subject: [PATCH] s390/pai: Fix missing PAI counter increments under heavy load MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Machines with a larger number of CPUs and under heavy load sometimes loose PAI counter increments during recording using events -e CRYPTO_ÂLL or -e NNPA_ALL. Counting is not affected. This happens when several PAI crypto counters are incremented during the same cryptographic operation. During schedule out the functions paiXXX_sched_task() (with XXX either crypt or ext) +--> pai_have_samples() +--> pai_have_sample() +--> pai_copy() +--> pai_push_sample() are called to read out PAI counter values. In pai_copy() the current values of PAI counters are read from the PMU memory mapped page and compared to the values read during last schedule out operation, which have been saved in a backup page named PAI_SAVE_AREA(event). For each PAI counter a delta is calculated and when the delta is positive, that PAI counter was incremented by hardware. This positve delta is reported as raw data record attached to a sample. After all deltas have been calculated, the new PAI counter values are saved in the backup page PAI_SAVE_AREA(event). However this is done in pai_push_sample(), leaving a small window for missing hardware triggered updates. Here is one scenario: PAI counter idx: 0 1 2 3 4 5 6 7 .... N +---+---+---+---+---+---+---+---+ +---+ PAI counter page:| | | X | | | | | |....| Y | +---+---+---+---+---+---+---+---+ +---+ In pai_copy() each PAI counter value is read and compared to its old value. This is done in a loop. When PAI counter indexed N is read, the hardware might increment PAI counter indexed 2 again, updating its value from X to X+1. Later pai_push_sample() simply mem-copies the complete PAI counter page to a backup page and the increment of X+1 is lost, because the backup page now contains the new value. Read each PAI counter and save this value in the backup page when there is a positive delta. This omits any time window between read and store. This also reduced the work load as only modified PAI counters are saved. Cc: stable@vger.kernel.org Fixes: fe861b0c8d06 ("s390/pai: save PAI counter value page in event structure") Signed-off-by: Thomas Richter Reviewed-by: Sumanth Korikkar Signed-off-by: Alexander Gordeev diff --git a/arch/s390/kernel/perf_pai.c b/arch/s390/kernel/perf_pai.c index f13c5c5fbea6..cdb8006220ca 100644 --- a/arch/s390/kernel/perf_pai.c +++ b/arch/s390/kernel/perf_pai.c @@ -186,6 +186,13 @@ static u64 pai_getctr(unsigned long *page, int nr, unsigned long offset) return page[nr]; } +static void pai_setctr(unsigned long *page, int nr, unsigned long offset, u64 v) +{ + if (offset) + nr += offset / sizeof(*page); + page[nr] = v; +} + /* Read the counter values. Return value from location in CMP. For base * event xxx_ALL sum up all events. Returns counter value. */ @@ -551,6 +558,8 @@ static void paicrypt_del(struct perf_event *event, int flags) /* Create raw data and save it in buffer. Calculate the delta for each * counter between this invocation and the last invocation. * Returns number of bytes copied. + * After reading from PAI counter page, save the read value to the old + * page to calculate PAI counter deltas. * Saves only entries with positive counter difference of the form * 2 bytes: Number of counter * 8 bytes: Value of counter @@ -562,16 +571,22 @@ static size_t pai_copy(struct pai_userdata *userdata, unsigned long *page, int i, outidx = 0; for (i = 1; i <= pp->num_avail; i++) { - u64 val = 0, val_old = 0; + u64 val = 0, val_old = 0, val_k = 0, val_old_k = 0; if (!exclude_kernel) { - val += pai_getctr(page, i, pp->kernel_offset); - val_old += pai_getctr(page_old, i, pp->kernel_offset); + val_k = pai_getctr(page, i, pp->kernel_offset); + val_old_k = pai_getctr(page_old, i, pp->kernel_offset); + if (val_k != val_old_k) + pai_setctr(page_old, i, pp->kernel_offset, val_k); } if (!exclude_user) { - val += pai_getctr(page, i, 0); - val_old += pai_getctr(page_old, i, 0); + val = pai_getctr(page, i, 0); + val_old = pai_getctr(page_old, i, 0); + if (val != val_old) + pai_setctr(page_old, i, 0, val); } + val += val_k; + val_old += val_old_k; if (val >= val_old) val -= val_old; else @@ -602,8 +617,6 @@ static size_t pai_copy(struct pai_userdata *userdata, unsigned long *page, static int pai_push_sample(size_t rawsize, struct pai_map *cpump, struct perf_event *event) { - int idx = PAI_PMU_IDX(event); - struct pai_pmu *pp = &pai_pmu[idx]; struct perf_sample_data data; struct perf_raw_record raw; struct pt_regs regs; @@ -634,8 +647,6 @@ static int pai_push_sample(size_t rawsize, struct pai_map *cpump, overflow = perf_event_overflow(event, &data, ®s); perf_event_update_userpage(event); - /* Save crypto counter lowcore page after reading event data. */ - memcpy((void *)PAI_SAVE_AREA(event), cpump->area, pp->area_size); return overflow; }