From 72bbc226ed2ef0a46c165a482861fff00dd6d4e1 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Tue, 23 Mar 2021 21:40:11 +0100 Subject: [PATCH 1/4] s390/vdso: copy tod_steering_delta value to vdso_data page When converting the vdso assembler code to C it was forgotten to actually copy the tod_steering_delta value to vdso_data page. Which in turn means that tod clock steering will not work correctly. Fix this by simply copying the value whenever it is updated. Fixes: 4bff8cb54502 ("s390: convert to GENERIC_VDSO") Cc: # 5.10 Signed-off-by: Heiko Carstens --- arch/s390/kernel/time.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c index 165da961f901..e37285a5101b 100644 --- a/arch/s390/kernel/time.c +++ b/arch/s390/kernel/time.c @@ -382,6 +382,7 @@ static void clock_sync_global(unsigned long delta) tod_steering_delta); tod_steering_end = now + (abs(tod_steering_delta) << 15); vdso_data->arch_data.tod_steering_end = tod_steering_end; + vdso_data->arch_data.tod_steering_delta = tod_steering_delta; /* Update LPAR offset. */ if (ptff_query(PTFF_QTO) && ptff(&qto, sizeof(qto), PTFF_QTO) == 0) From b24bacd67ffddd9192c4745500fd6f73dbfe565e Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Wed, 24 Mar 2021 20:22:42 +0100 Subject: [PATCH 2/4] s390/vdso: fix tod_steering_delta type The s390 specific vdso function __arch_get_hw_counter() is supposed to consider tod clock steering. If a tod clock steering event happens and the tod clock is set to a new value __arch_get_hw_counter() will not return the real tod clock value but slowly drift it from the old delta until the returned value finally matches the real tod clock value again. Unfortunately the type of tod_steering_delta unsigned while it is supposed to be signed. It depends on if tod_steering_delta is negative or positive in which direction the vdso code drifts the clock value. Worst case is now that instead of drifting the clock slowly it will jump into the opposite direction by a factor of two. Fix this by simply making tod_steering_delta signed. Fixes: 4bff8cb54502 ("s390: convert to GENERIC_VDSO") Cc: # 5.10 Signed-off-by: Heiko Carstens --- arch/s390/include/asm/vdso/data.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/s390/include/asm/vdso/data.h b/arch/s390/include/asm/vdso/data.h index 7b3cdb4a5f48..73ee89142666 100644 --- a/arch/s390/include/asm/vdso/data.h +++ b/arch/s390/include/asm/vdso/data.h @@ -6,7 +6,7 @@ #include struct arch_vdso_data { - __u64 tod_steering_delta; + __s64 tod_steering_delta; __u64 tod_steering_end; }; From 5b43bd184530af6b868d8273b0a743a138d37ee8 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Wed, 24 Mar 2021 20:23:55 +0100 Subject: [PATCH 3/4] s390/vdso: fix initializing and updating of vdso_data Li Wang reported that clock_gettime(CLOCK_MONOTONIC_RAW, ...) returns incorrect values when time is provided via vdso instead of system call: vdso_ts_nsec = 4484351380985507, vdso_ts.tv_sec = 4484351, vdso_ts.tv_nsec = 380985507 sys_ts_nsec = 1446923235377, sys_ts.tv_sec = 1446, sys_ts.tv_nsec = 923235377 Within the s390 specific vdso function __arch_get_hw_counter() reads tod clock steering values from the arch_data member of the passed in vdso_data structure. Problem is that only for the CS_HRES_COARSE vdso_data arch_data is initialized and gets updated. The CS_RAW specific vdso_data does not contain any valid tod_clock_steering information, which explains the different values. Fix this by initializing and updating all vdso_datas. Reported-by: Li Wang Tested-by: Li Wang Fixes: 1ba2d6c0fd4e ("s390/vdso: simplify __arch_get_hw_counter()") Link: https://lore.kernel.org/linux-s390/YFnxr1ZlMIOIqjfq@osiris Signed-off-by: Heiko Carstens --- arch/s390/kernel/time.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c index e37285a5101b..326cb8f75f58 100644 --- a/arch/s390/kernel/time.c +++ b/arch/s390/kernel/time.c @@ -80,10 +80,12 @@ void __init time_early_init(void) { struct ptff_qto qto; struct ptff_qui qui; + int cs; /* Initialize TOD steering parameters */ tod_steering_end = tod_clock_base.tod; - vdso_data->arch_data.tod_steering_end = tod_steering_end; + for (cs = 0; cs < CS_BASES; cs++) + vdso_data[cs].arch_data.tod_steering_end = tod_steering_end; if (!test_facility(28)) return; @@ -366,6 +368,7 @@ static void clock_sync_global(unsigned long delta) { unsigned long now, adj; struct ptff_qto qto; + int cs; /* Fixup the monotonic sched clock. */ tod_clock_base.eitod += delta; @@ -381,8 +384,10 @@ static void clock_sync_global(unsigned long delta) panic("TOD clock sync offset %li is too large to drift\n", tod_steering_delta); tod_steering_end = now + (abs(tod_steering_delta) << 15); - vdso_data->arch_data.tod_steering_end = tod_steering_end; - vdso_data->arch_data.tod_steering_delta = tod_steering_delta; + for (cs = 0; cs < CS_BASES; cs++) { + vdso_data[cs].arch_data.tod_steering_end = tod_steering_end; + vdso_data[cs].arch_data.tod_steering_delta = tod_steering_delta; + } /* Update LPAR offset. */ if (ptff_query(PTFF_QTO) && ptff(&qto, sizeof(qto), PTFF_QTO) == 0) From 84d572e634e28827d105746c922d8ada425e2d8b Mon Sep 17 00:00:00 2001 From: Matthew Rosato Date: Thu, 25 Mar 2021 09:41:52 -0400 Subject: [PATCH 4/4] MAINTAINERS: add backups for s390 vfio drivers Add a backup for s390 vfio-pci, an additional backup for vfio-ccw and replace the backup for vfio-ap as Pierre is focusing on other areas. Signed-off-by: Matthew Rosato Acked-by: Eric Farman Acked-by: Halil Pasic Acked-by: Pierre Morel Acked-by: Jason J. Herne Link: https://lore.kernel.org/r/1616679712-7139-1-git-send-email-mjrosato@linux.ibm.com Signed-off-by: Christian Borntraeger Signed-off-by: Heiko Carstens --- MAINTAINERS | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/MAINTAINERS b/MAINTAINERS index 9e876927c60d..68a562374b85 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -15634,8 +15634,8 @@ F: Documentation/s390/pci.rst S390 VFIO AP DRIVER M: Tony Krowiak -M: Pierre Morel M: Halil Pasic +M: Jason Herne L: linux-s390@vger.kernel.org S: Supported W: http://www.ibm.com/developerworks/linux/linux390/ @@ -15647,6 +15647,7 @@ F: drivers/s390/crypto/vfio_ap_private.h S390 VFIO-CCW DRIVER M: Cornelia Huck M: Eric Farman +M: Matthew Rosato R: Halil Pasic L: linux-s390@vger.kernel.org L: kvm@vger.kernel.org @@ -15657,6 +15658,7 @@ F: include/uapi/linux/vfio_ccw.h S390 VFIO-PCI DRIVER M: Matthew Rosato +M: Eric Farman L: linux-s390@vger.kernel.org L: kvm@vger.kernel.org S: Supported