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

5 files changed, 11 insertions, 4 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_irq_kms.c b/drivers/gpu/drm/radeon/radeon_irq_kms.c
index 9961251b44ba..d550554a6f3f 100644
--- a/drivers/gpu/drm/radeon/radeon_irq_kms.c
+++ b/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 */
diff --git a/drivers/net/ethernet/pensando/ionic/ionic_bus_pci.c b/drivers/net/ethernet/pensando/ionic/ionic_bus_pci.c
index 70d86c5f52fb..0671deae9a28 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_bus_pci.c
+++ b/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);
diff --git a/drivers/pci/msi/msi.c b/drivers/pci/msi/msi.c
index e010ecd9f90d..fb9a42bec62e 100644
--- a/drivers/pci/msi/msi.c
+++ b/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) {
diff --git a/drivers/pci/msi/pcidev_msi.c b/drivers/pci/msi/pcidev_msi.c
index 5520aff53b56..0b0346813092 100644
--- a/drivers/pci/msi/pcidev_msi.c
+++ b/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)
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 41183aed8f5d..a2bff57176a3 100644
--- a/drivers/pci/probe.c
+++ b/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));