PCI/MSI: Convert the boolean no_64bit_msi flag to a DMA address mask

Some PCI devices have PCI_MSI_FLAGS_64BIT in the MSI capability, but
implement less than 64 address bits. This breaks on platforms where such
a device is assigned an MSI address higher than what's supported.

Currently, no_64bit_msi bit is set for these devices, meaning that only
32-bit MSI addresses are allowed for them. However, on some platforms the
MSI doorbell address is above the 32-bit limit but within the addressable
range of the device.

As a first step to enable MSI on those combinations of devices and
platforms, convert the boolean no_64bit_msi flag to a DMA mask and fixup
the affected usage sites:

  - no_64bit_msi = 1    ->    msi_addr_mask = DMA_BIT_MASK(32)
  - no_64bit_msi = 0    ->    msi_addr_mask = DMA_BIT_MASK(64)
  - if (no_64bit_msi)   ->    if (msi_addr_mask < DMA_BIT_MASK(64))

Since no values other than DMA_BIT_MASK(32) and DMA_BIT_MASK(64) are used,
this is functionally equivalent.

This prepares for changing the binary decision between 32 and 64 bit to a
DMA mask based decision which allows to support systems which have a DMA
address space less than 64bit but a MSI doorbell address above the 32-bit
limit.

[ tglx: Massaged changelog ]

Signed-off-by: Vivian Wang <wangruikang@iscas.ac.cn>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Brett Creeley <brett.creeley@amd.com> # ionic
Reviewed-by: Thomas Gleixner <tglx@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de> # sound
Link: https://patch.msgid.link/20260129-pci-msi-addr-mask-v4-1-70da998f2750@iscas.ac.cn

arch/powerpc/platforms/powernv/pci-ioda.c

@@ -1666,7 +1666,7 @@ static int __pnv_pci_ioda_msi_setup(struct pnv_phb *phb, struct pci_dev *dev,
 		return -ENXIO;
 
 	/* Force 32-bit MSI on some broken devices */
-	if (dev->no_64bit_msi)
+	if (dev->msi_addr_mask < DMA_BIT_MASK(64))
 		is_64 = 0;
 
 	/* Assign XIVE to PE */

arch/powerpc/platforms/pseries/msi.c

@@ -383,7 +383,7 @@ static int rtas_prepare_msi_irqs(struct pci_dev *pdev, int nvec_in, int type,
 	 */
 again:
 	if (type == PCI_CAP_ID_MSI) {
-		if (pdev->no_64bit_msi) {
+		if (pdev->msi_addr_mask < DMA_BIT_MASK(64)) {
 			rc = rtas_change_msi(pdn, RTAS_CHANGE_32MSI_FN, nvec);
 			if (rc < 0) {
 				/*
@@ -409,7 +409,7 @@ again:
 		if (use_32bit_msi_hack && rc > 0)
 			rtas_hack_32bit_msi_gen2(pdev);
 	} else {
-		if (pdev->no_64bit_msi)
+		if (pdev->msi_addr_mask < DMA_BIT_MASK(64))
 			rc = rtas_change_msi(pdn, RTAS_CHANGE_32MSIX_FN, nvec);
 		else
 			rc = rtas_change_msi(pdn, RTAS_CHANGE_MSIX_FN, nvec);

drivers/gpu/drm/radeon/radeon_irq_kms.c

@@ -252,7 +252,7 @@ static bool radeon_msi_ok(struct radeon_device *rdev)
 	 */
 	if (rdev->family < CHIP_BONAIRE) {
 		dev_info(rdev->dev, "radeon: MSI limited to 32-bit\n");
-		rdev->pdev->no_64bit_msi = 1;
+		rdev->pdev->msi_addr_mask = DMA_BIT_MASK(32);
 	}
 
 	/* force MSI on */

drivers/net/ethernet/pensando/ionic/ionic_bus_pci.c

@@ -331,7 +331,7 @@ static int ionic_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 
 #ifdef CONFIG_PPC64
 	/* Ensure MSI/MSI-X interrupts lie within addressable physical memory */
-	pdev->no_64bit_msi = 1;
+	pdev->msi_addr_mask = DMA_BIT_MASK(32);
 #endif
 
 	err = ionic_setup_one(ionic);

drivers/pci/msi/msi.c

@@ -322,7 +322,7 @@ static int msi_verify_entries(struct pci_dev *dev)
 {
 	struct msi_desc *entry;
 
-	if (!dev->no_64bit_msi)
+	if (dev->msi_addr_mask == DMA_BIT_MASK(64))
 		return 0;
 
 	msi_for_each_desc(entry, &dev->dev, MSI_DESC_ALL) {

drivers/pci/msi/pcidev_msi.c

@@ -24,7 +24,7 @@ void pci_msi_init(struct pci_dev *dev)
 	}
 
 	if (!(ctrl & PCI_MSI_FLAGS_64BIT))
-		dev->no_64bit_msi = 1;
+		dev->msi_addr_mask = DMA_BIT_MASK(32);
 }
 
 void pci_msix_init(struct pci_dev *dev)

drivers/pci/probe.c

@@ -2047,6 +2047,13 @@ int pci_setup_device(struct pci_dev *dev)
 	 */
 	dev->dma_mask = 0xffffffff;
 
+	/*
+	 * Assume 64-bit addresses for MSI initially. Will be changed to 32-bit
+	 * if MSI (rather than MSI-X) capability does not have
+	 * PCI_MSI_FLAGS_64BIT. Can also be overridden by driver.
+	 */
+	dev->msi_addr_mask = DMA_BIT_MASK(64);
+
 	dev_set_name(&dev->dev, "%04x:%02x:%02x.%d", pci_domain_nr(dev->bus),
 		     dev->bus->number, PCI_SLOT(dev->devfn),
 		     PCI_FUNC(dev->devfn));

include/linux/pci.h

@@ -377,6 +377,13 @@ struct pci_dev {
 					   0xffffffff.  You only need to change
 					   this if your device has broken DMA
 					   or supports 64-bit transfers.  */
+	u64		msi_addr_mask;	/* Mask of the bits of bus address for
+					   MSI that this device implements.
+					   Normally set based on device
+					   capabilities. You only need to
+					   change this if your device claims
+					   to support 64-bit MSI but implements
+					   fewer than 64 address bits. */
 
 	struct device_dma_parameters dma_parms;
 
@@ -441,7 +448,6 @@ struct pci_dev {
 
 	unsigned int	is_busmaster:1;		/* Is busmaster */
 	unsigned int	no_msi:1;		/* May not use MSI */
-	unsigned int	no_64bit_msi:1;		/* May only use 32-bit MSIs */
 	unsigned int	block_cfg_access:1;	/* Config space access blocked */
 	unsigned int	broken_parity_status:1;	/* Generates false positive parity */
 	unsigned int	irq_reroute_variant:2;	/* Needs IRQ rerouting variant */

sound/hda/controllers/intel.c

@@ -1905,7 +1905,7 @@ static int azx_first_init(struct azx *chip)
 
 	if (chip->msi && chip->driver_caps & AZX_DCAPS_NO_MSI64) {
 		dev_dbg(card->dev, "Disabling 64bit MSI\n");
-		pci->no_64bit_msi = true;
+		pci->msi_addr_mask = DMA_BIT_MASK(32);
 	}
 
 	pci_set_master(pci);