Add fixup patch for MSI-X handling

QubesOS/qubes-issues#4799
QubesOS/qubes-issues#7057
QubesOS/qubes-issues#7052

0001-xen-pciback-Consider-INTx-disabled-when-MSI-MSI-X-is.patch

@@ -0,0 +1,82 @@
+From 7336f034ba268aa2d3bf944e18b6a63e704799c1 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?=
+ <[email protected]>
+Date: Thu, 17 Nov 2022 12:35:41 +0100
+Subject: [PATCH] xen-pciback: Consider INTx disabled when MSI/MSI-X is enabled
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Linux enables MSI-X before disabling INTx, but keeps MSI-X masked until
+the table is filled. Then it disables INTx just before clearing MASKALL
+bit. Currently this approach is rejected by xen-pciback.
+According to the PCIe spec, device cannot use INTx when MSI/MSI-X is
+enabled. Change the logic to consider INTx disabled if MSI/MSI-X is
+enabled. This applies to two places: checking currently enabled
+interrupts type, and transition to MSI/MSI-X - where INTx would be
+implicitly disabled.
+
+Fixes: 5e29500eba2a ("xen-pciback: Allow setting PCI_MSIX_FLAGS_MASKALL too")
+Signed-off-by: Marek Marczykowski-Górecki <[email protected]>
+---
+ drivers/xen/xen-pciback/conf_space.c          | 19 +++++++++++++------
+ .../xen/xen-pciback/conf_space_capability.c   |  3 ++-
+ 2 files changed, 15 insertions(+), 7 deletions(-)
+
+diff --git a/drivers/xen/xen-pciback/conf_space.c b/drivers/xen/xen-pciback/conf_space.c
+index 059de92aea7d..d47eee6c5143 100644
+--- a/drivers/xen/xen-pciback/conf_space.c
++++ b/drivers/xen/xen-pciback/conf_space.c
+@@ -288,12 +288,6 @@ int xen_pcibk_get_interrupt_type(struct pci_dev *dev)
+ 	u16 val;
+ 	int ret = 0;
+
+-	err = pci_read_config_word(dev, PCI_COMMAND, &val);
+-	if (err)
+-		return err;
+-	if (!(val & PCI_COMMAND_INTX_DISABLE))
+-		ret |= INTERRUPT_TYPE_INTX;
+-
+ 	/*
+ 	 * Do not trust dev->msi(x)_enabled here, as enabling could be done
+ 	 * bypassing the pci_*msi* functions, by the qemu.
+@@ -316,6 +310,19 @@ int xen_pcibk_get_interrupt_type(struct pci_dev *dev)
+ 		if (val & PCI_MSIX_FLAGS_ENABLE)
+ 			ret |= INTERRUPT_TYPE_MSIX;
+ 	}
++
++	/*
++	 * PCIe spec says device cannot use INTx if MSI/MSI-X is enabled,
++	 * so check for INTx only when both are disabled.
++	 */
++	if (!ret) {
++		err = pci_read_config_word(dev, PCI_COMMAND, &val);
++		if (err)
++			return err;
++		if (!(val & PCI_COMMAND_INTX_DISABLE))
++			ret |= INTERRUPT_TYPE_INTX;
++	}
++
+ 	return ret ?: INTERRUPT_TYPE_NONE;
+ }
+
+diff --git a/drivers/xen/xen-pciback/conf_space_capability.c b/drivers/xen/xen-pciback/conf_space_capability.c
+index 097316a74126..eb4c1af44f5c 100644
+--- a/drivers/xen/xen-pciback/conf_space_capability.c
++++ b/drivers/xen/xen-pciback/conf_space_capability.c
+@@ -236,10 +236,11 @@ static int msi_msix_flags_write(struct pci_dev *dev, int offset, u16 new_value,
+ 		return PCIBIOS_SET_FAILED;
+
+ 	if (new_value & field_config->enable_bit) {
+-		/* don't allow enabling together with other interrupt types */
++		/* don't allow enabling together with other interrupt type */
+ 		int int_type = xen_pcibk_get_interrupt_type(dev);
+
+ 		if (int_type == INTERRUPT_TYPE_NONE ||
++		    int_type == INTERRUPT_TYPE_INTX ||
+ 		    int_type == field_config->int_type)
+ 			goto write;
+ 		return PCIBIOS_SET_FAILED;
+-- 
+2.37.3
+

kernel.spec.in

@@ -144,6 +144,7 @@ Patch25: 0001-Re-enable-interrupts-before-loading-PNVM.patch
 Patch26: 0001-sound-Disable-SG-buffer.patch
 Patch27: 0001-amdgpu-timeout.patch
 Patch28: 0001-iwlwifi-avoid-writing-to-MSI-X-page-when-MSI-X-is-no.patch
+Patch29: 0001-xen-pciback-Consider-INTx-disabled-when-MSI-MSI-X-is.patch
 
 # S0ix support:
 Patch61: xen-events-Add-wakeup-support-to-xen-pirq.patch