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Wed, 28 Oct 2026 15:44:00 +0000 (GMT) Received: from Mac.ibm.com (unknown [9.61.240.205]) by smtpav04.wdc07v.mail.ibm.com (Postfix) with ESMTP; Wed, 28 Oct 2026 15:44:00 +0000 (GMT) From: Omar Elghoul To: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, schnelle@linux.ibm.com, mjrosato@linux.ibm.com, alifm@linux.ibm.com, farman@linux.ibm.com, gbayer@linux.ibm.com, pasic@linux.ibm.com, alex@shazbot.org, frankja@linux.ibm.com, imbrenda@linux.ibm.com Subject: [PATCH v11 2/5] s390/pci: Improve function measurement state management Date: Wed, 28 Oct 2026 11:43:49 -0400 Message-ID: <20261028154352.15108-3-oelghoul@linux.ibm.com> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028154352.15108-1-oelghoul@linux.ibm.com> References: <20261028154352.15108-1-oelghoul@linux.ibm.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDI4MDA2MiBTYWx0ZWRfX6MZzm6P0VUKt 9wg/bbjL4/8fsOiM6d1PVX+CdgcHzkerg/K6qaHWZkMXrzSOXLsG18ll3epPaVVdpN6JJ119y1P APiQO/F/IVjKnbxJbGcLiosftYdGhntIV88DOrkFD13p9DAgvpfB1HlZq0n9/wnJ3LPfssHTr8t Ss6j9CcmsYzZZ/yflEo1ZW7AeYqVKxxsM/9toHCEsdQs9JfnsGTMRmo/il18nJaEc9qFtCTzQX6 WPaEAQhei4jW1rbIvq26GAoAmPmLmYl8une6Dnd1kV4mg4nG+d83bnPL9jZC1jiUhUV4T5j2Bq3 lAJo63jcFR9yk1hZMgaot8wOO2E1gaI7BPot2kKQnTc3bHgVDyKsfFH+jiZxtGxYNe0EhQQSNO1 p8kQfVmHnlg5k28GyN1gRju0muYY9IVa11KW0CVuUzBHPp2eRiN+LnRRdjEWKCWZscIgxW6A7aE 6X6Aq8CNdLa/rdAe/Hg== X-Proofpoint-Spam-Info: AW1haW4tMjYxMDI4MDA2MiBTYWx0ZWRfXxstWNkGZX2A0 CTIDc7PBp+xmlX6AxrZFm7qnseogotWBLObGDTFVjfuVqbUdwzDFaUL2WAkueCzTmMo6GAuqFL1 ghnK2LBdHz33zHxmZMAZPHLzWfYeG4Q= X-Proofpoint-ORIG-GUID: E-em-Ome7uFfRDNW1JAu51jt_qIVmxP- X-Proofpoint-GUID: E-em-Ome7uFfRDNW1JAu51jt_qIVmxP- X-Authority-Analysis: v=2.4 cv=CeKdd7rl c=1 sm=1 tr=0 ts=6ae21847 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=660iZSQnnn4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VnNF1IyMAAAA:8 a=cItLoxOyQSrHz8uLRusA:9 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.138,FMLib:17.12.100.49 definitions=2026-10-28_05,2026-10-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 clxscore=1015 adultscore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610190000 definitions=main-2610280062 When a zPCI function is disabled and re-enabled, the firmware implicitly disables function measurement while the kernel still believes it is enabled, leading to a disconnect between the user-visible state and the actual device state. Add the statistics_on field to struct zpci_dev to track the desired FMB state. Introduce the functions zpci_fmb_request_on() and off(), which defer to zpci_fmb_enable() or disable() to perform the actual firmware change. This decouples the enablement or disablement step from managing the user's requested state. Preserve the state in pcibios_enable_device(), pcibios_disable_device(), and zpci_reenable_device(), so measurement is restored automatically after a re-enable. New devices start with measurement on by default, unchanged from before. Signed-off-by: Omar Elghoul --- arch/s390/include/asm/pci.h | 7 +++-- arch/s390/pci/pci.c | 60 +++++++++++++++++++++++++++++++++---- arch/s390/pci/pci_debug.c | 6 ++-- 3 files changed, 63 insertions(+), 10 deletions(-) diff --git a/arch/s390/include/asm/pci.h b/arch/s390/include/asm/pci.h index 88a125b92bdd..dd7a17955362 100644 --- a/arch/s390/include/asm/pci.h +++ b/arch/s390/include/asm/pci.h @@ -208,6 +208,7 @@ struct zpci_dev { struct zpci_fmb *fmb; u16 fmb_update; /* update interval */ u16 fmb_length; + bool statistics_on; /* desired FMB enablement */ u8 version; enum pci_bus_speed max_bus_speed; @@ -349,8 +350,10 @@ int zpci_create_parent_msi_domain(struct zpci_bus *zbus); void zpci_remove_parent_msi_domain(struct zpci_bus *zbus); /* FMB */ -int zpci_fmb_enable_device(struct zpci_dev *); -int zpci_fmb_disable_device(struct zpci_dev *); +int zpci_fmb_request_on(struct zpci_dev *zdev); +int zpci_fmb_request_off(struct zpci_dev *zdev); +int zpci_fmb_enable(struct zpci_dev *zdev); +int zpci_fmb_disable(struct zpci_dev *zdev); /* Debug */ int zpci_debug_init(void); diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c index c055a9ad0972..5889dd227009 100644 --- a/arch/s390/pci/pci.c +++ b/arch/s390/pci/pci.c @@ -164,8 +164,44 @@ int zpci_unregister_ioat(struct zpci_dev *zdev, u8 dmaas) return cc; } +int zpci_fmb_request_on(struct zpci_dev *zdev) +{ + int rc; + + lockdep_assert_held(&zdev->fmb_lock); + + if (zdev->statistics_on) + return -EINVAL; + + rc = zpci_fmb_enable(zdev); + if (rc) + return rc; + + zdev->statistics_on = true; + return 0; +} +EXPORT_SYMBOL_GPL(zpci_fmb_request_on); + +int zpci_fmb_request_off(struct zpci_dev *zdev) +{ + int rc; + + lockdep_assert_held(&zdev->fmb_lock); + + if (!zdev->statistics_on) + return -EINVAL; + + rc = zpci_fmb_disable(zdev); + if (rc) + return rc; + + zdev->statistics_on = false; + return 0; +} +EXPORT_SYMBOL_GPL(zpci_fmb_request_off); + /* Modify PCI: Set PCI function measurement parameters */ -int zpci_fmb_enable_device(struct zpci_dev *zdev) +int zpci_fmb_enable(struct zpci_dev *zdev) { u64 req = ZPCI_CREATE_REQ(zdev->fh, 0, ZPCI_MOD_FC_SET_MEASURE); struct zpci_iommu_ctrs *ctrs; @@ -207,7 +243,7 @@ int zpci_fmb_enable_device(struct zpci_dev *zdev) } /* Modify PCI: Disable PCI function measurement */ -int zpci_fmb_disable_device(struct zpci_dev *zdev) +int zpci_fmb_disable(struct zpci_dev *zdev) { u64 req = ZPCI_CREATE_REQ(zdev->fh, 0, ZPCI_MOD_FC_SET_MEASURE); struct zpci_fib fib = {0}; @@ -644,7 +680,8 @@ int pcibios_enable_device(struct pci_dev *pdev, int mask) zpci_debug_init_device(zdev, dev_name(&pdev->dev)); mutex_lock(&zdev->fmb_lock); - zpci_fmb_enable_device(zdev); + if (zdev->statistics_on) + zpci_fmb_enable(zdev); mutex_unlock(&zdev->fmb_lock); return pci_enable_resources(pdev, mask); @@ -655,7 +692,8 @@ void pcibios_disable_device(struct pci_dev *pdev) struct zpci_dev *zdev = to_zpci(pdev); mutex_lock(&zdev->fmb_lock); - zpci_fmb_disable_device(zdev); + if (zdev->statistics_on) + zpci_fmb_disable(zdev); mutex_unlock(&zdev->fmb_lock); zpci_debug_exit_device(zdev); } @@ -737,8 +775,14 @@ int zpci_reenable_device(struct zpci_dev *zdev) } rc = zpci_iommu_register_ioat(zdev, &status); - if (rc) + if (rc) { zpci_disable_device(zdev); + return rc; + } + + guard(mutex)(&zdev->fmb_lock); + if (zdev->statistics_on) + zpci_fmb_enable(zdev); return rc; } @@ -847,6 +891,12 @@ struct zpci_dev *zpci_create_device(u32 fid, u32 fh, enum zpci_state state) goto error; zdev->state = state; + /* + * Measurement is on by default for new functions, this will be honored + * by pcibios_enable_device(). + */ + zdev->statistics_on = true; + mutex_init(&zdev->state_lock); mutex_init(&zdev->fmb_lock); mutex_init(&zdev->kzdev_lock); diff --git a/arch/s390/pci/pci_debug.c b/arch/s390/pci/pci_debug.c index c7ed7bf254b5..e479763858cd 100644 --- a/arch/s390/pci/pci_debug.c +++ b/arch/s390/pci/pci_debug.c @@ -97,7 +97,7 @@ static int pci_perf_show(struct seq_file *m, void *v) return 0; mutex_lock(&zdev->fmb_lock); - if (!zdev->fmb) { + if (!zdev->statistics_on || !zdev->fmb) { mutex_unlock(&zdev->fmb_lock); seq_puts(m, "FMB statistics disabled\n"); return 0; @@ -156,10 +156,10 @@ static ssize_t pci_perf_seq_write(struct file *file, const char __user *ubuf, mutex_lock(&zdev->fmb_lock); switch (val) { case 0: - rc = zpci_fmb_disable_device(zdev); + rc = zpci_fmb_request_off(zdev); break; case 1: - rc = zpci_fmb_enable_device(zdev); + rc = zpci_fmb_request_on(zdev); break; } mutex_unlock(&zdev->fmb_lock); -- 2.56.0