From: Matthew Rosato <mjrosato@linux.ibm.com>
Date: Thu, 10 Sep 2020 10:59:57 -0400
Subject: vfio/pci: Decouple PCI_COMMAND_MEMORY bit checks from is_virtfn
Git-commit: 515ecd5368f1510152fa4f9b9ce55b66ac56c334
Patch-mainline: v5.10-rc1
References: bsc#1179612

While it is true that devices with is_virtfn=1 will have a Memory Space
Enable bit that is hard-wired to 0, this is not the only case where we
see this behavior -- For example some bare-metal hypervisors lack
Memory Space Enable bit emulation for devices not setting is_virtfn
(s390). Fix this by instead checking for the newly-added
no_command_memory bit which directly denotes the need for
PCI_COMMAND_MEMORY emulation in vfio.

Fixes: abafbc551fdd ("vfio-pci: Invalidate mmaps and block MMIO access on disabled memory")
Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Acked-by: Joerg Roedel <jroedel@suse.de>
---
 drivers/vfio/pci/vfio_pci_config.c |   24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

--- a/drivers/vfio/pci/vfio_pci_config.c
+++ b/drivers/vfio/pci/vfio_pci_config.c
@@ -409,7 +409,7 @@ bool __vfio_pci_memory_enabled(struct vf
 	 * PF SR-IOV capability, there's therefore no need to trigger
 	 * faults based on the virtual value.
 	 */
-	return pdev->is_virtfn || (cmd & PCI_COMMAND_MEMORY);
+	return pdev->no_command_memory || (cmd & PCI_COMMAND_MEMORY);
 }
 
 /*
@@ -522,8 +522,8 @@ static int vfio_basic_config_read(struct
 
 	count = vfio_default_config_read(vdev, pos, count, perm, offset, val);
 
-	/* Mask in virtual memory enable for SR-IOV devices */
-	if (offset == PCI_COMMAND && vdev->pdev->is_virtfn) {
+	/* Mask in virtual memory enable */
+	if (offset == PCI_COMMAND && vdev->pdev->no_command_memory) {
 		u16 cmd = le16_to_cpu(*(__le16 *)&vdev->vconfig[PCI_COMMAND]);
 		u32 tmp_val = le32_to_cpu(*val);
 
@@ -591,9 +591,11 @@ static int vfio_basic_config_write(struc
 		 * shows it disabled (phys_mem/io, then the device has
 		 * undergone some kind of backdoor reset and needs to be
 		 * restored before we allow it to enable the bars.
-		 * SR-IOV devices will trigger this, but we catch them later
+		 * SR-IOV devices will trigger this - for mem enable let's
+		 * catch this now and for io enable it will be caught later
 		 */
-		if ((new_mem && virt_mem && !phys_mem) ||
+		if ((new_mem && virt_mem && !phys_mem &&
+		     !pdev->no_command_memory) ||
 		    (new_io && virt_io && !phys_io) ||
 		    vfio_need_bar_restore(vdev))
 			vfio_bar_restore(vdev);
@@ -1699,12 +1701,14 @@ int vfio_config_init(struct vfio_pci_dev
 	if (pdev->is_virtfn) {
 		*(__le16 *)&vconfig[PCI_VENDOR_ID] = cpu_to_le16(pdev->vendor);
 		*(__le16 *)&vconfig[PCI_DEVICE_ID] = cpu_to_le16(pdev->device);
-
+	}
+	if (pdev->no_command_memory) {
 		/*
-		 * VFs do no implement the memory enable bit of the COMMAND
-		 * register therefore we'll not have it set in our initial
-		 * copy of config space after pci_enable_device().  For
-		 * consistency with PFs, set the virtual enable bit here.
+		 * VFs and devices that set pdev->no_command_memory do not
+		 * implement the memory enable bit of the COMMAND register
+		 * therefore we'll not have it set in our initial copy of
+		 * config space after pci_enable_device().  For consistency
+		 * with PFs, set the virtual enable bit here.
 		 */
 		*(__le16 *)&vconfig[PCI_COMMAND] |=
 					cpu_to_le16(PCI_COMMAND_MEMORY);