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From: Matthew Rosato <mjrosato@linux.ibm.com>
To: alex.williamson@redhat.com, pmorel@linux.ibm.com, schnelle@linux.ibm.com
Cc: david@redhat.com, cohuck@redhat.com, qemu-devel@nongnu.org,
	pasic@linux.ibm.com, borntraeger@de.ibm.com,
	qemu-s390x@nongnu.org, rth@twiddle.net
Subject: [RFC PATCH] s390x/pci: Enforce PCI_COMMAND_MEMORY for vfio-pci
Date: Thu, 23 Jul 2020 11:13:56 -0400	[thread overview]
Message-ID: <1595517236-17823-2-git-send-email-mjrosato@linux.ibm.com> (raw)
In-Reply-To: <1595517236-17823-1-git-send-email-mjrosato@linux.ibm.com>

After kernel commit abafbc55 'vfio-pci: Invalidate mmaps and
block MMIO access on disabled memory', I'm seeing qemu errors
on s390x as vfio-pci devices attempt to read bar 0 because
PCI_COMMAND_MEMORY is not reliably set.  Ensure the value
stays ON while the device is in-use.

Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
---
 hw/s390x/s390-pci-inst.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/hw/s390x/s390-pci-inst.c b/hw/s390x/s390-pci-inst.c
index 2f7a7d7..74b8796 100644
--- a/hw/s390x/s390-pci-inst.c
+++ b/hw/s390x/s390-pci-inst.c
@@ -555,6 +555,16 @@ int pcistg_service_call(S390CPU *cpu, uint8_t r1, uint8_t r2, uintptr_t ra)
         }
         /* len = 1,2,4 so we do not need to test */
         zpci_endian_swap(&data, len);
+
+        /*
+         * vfio-pci requires PCI_COMMAND_MEMORY.  Ensure that it
+         * stays on for an active device.
+         */
+        if ((pbdev->fh & FH_SHM_VFIO) && (offset == PCI_COMMAND) &&
+            (len == 2) && (data != 0)) {
+            data |= PCI_COMMAND_MEMORY;
+        }
+
         pci_host_config_write_common(pbdev->pdev, offset,
                                      pci_config_size(pbdev->pdev),
                                      data, len);
-- 
1.8.3.1



  reply	other threads:[~2020-07-23 15:16 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-23 15:13 [RFC PATCH] s390x/pci: vfio-pci breakage with disabled mem enforcement Matthew Rosato
2020-07-23 15:13 ` Matthew Rosato [this message]
2020-07-23 16:29 ` Alex Williamson
2020-07-23 18:12   ` Matthew Rosato
2020-07-27 15:40   ` Pierre Morel
2020-07-27 16:37     ` Matthew Rosato
2020-07-27 16:47     ` Alex Williamson
2020-07-28  9:33       ` Niklas Schnelle
2020-07-28 12:52         ` Alex Williamson
2020-07-28 14:13           ` Niklas Schnelle
2020-07-28  8:59     ` Niklas Schnelle
2020-07-24  9:46 ` Niklas Schnelle
2020-07-24  9:53   ` Niklas Schnelle
2020-07-24 14:15   ` Niklas Schnelle

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