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Message-ID: <874iofs7dz.wl-tiwai@suse.de>
Date: Wed, 21 Jan 2026 09:21:44 +0100
From: Takashi Iwai <tiwai@...e.de>
To: Vivian Wang <wangruikang@...as.ac.cn>
Cc: Madhavan Srinivasan <maddy@...ux.ibm.com>, Michael Ellerman
<mpe@...erman.id.au>, Nicholas Piggin <npiggin@...il.com>,
"Christophe Leroy (CS GROUP)" <chleroy@...nel.org>, Alex Deucher
<alexander.deucher@....com>, Christian König
<christian.koenig@....com>, David Airlie <airlied@...il.com>, Simona Vetter
<simona@...ll.ch>, "Creeley, Brett" <bcreeley@....com>, Andrew Lunn
<andrew+netdev@...n.ch>, "David S. Miller" <davem@...emloft.net>, Eric
Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo
Abeni <pabeni@...hat.com>, Bjorn Helgaas <bhelgaas@...gle.com>, Jaroslav
Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>, Han Gao
<gaohan@...as.ac.cn>, linuxppc-dev@...ts.ozlabs.org,
linux-kernel@...r.kernel.org, amd-gfx@...ts.freedesktop.org,
dri-devel@...ts.freedesktop.org, netdev@...r.kernel.org,
linux-pci@...r.kernel.org, linux-sound@...r.kernel.org,
linux-riscv@...ts.infradead.org, sophgo@...ts.linux.dev
Subject: Re: [PATCH v2 1/4] PCI/MSI: Conservatively generalize no_64bit_msi into msi_addr_mask
On Wed, 21 Jan 2026 04:49:37 +0100,
Vivian Wang wrote:
>
> 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 reachable.
>
> Currently, we deal with this with a single no_64bit_msi flag, and
> (notably on powerpc) forces 32-bit MSI address for these devices.
> However, on some platforms the MSI doorbell address is above 32-bit but
> within device ability.
>
> As a first step to enabling MSI on those combinations of devices and
> platforms, conservatively generalize the single-bit flag no_64bit_msi
> into msi_addr_mask. (The name msi_addr_mask is chosen to avoid confusion
> with msi_mask.)
>
> The translation is essentially:
>
> - 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) is
> used, no functional change is intended. Future patches that make use of
> intermediate values of msi_addr_mask will follow, allowing devices that
> cannot use full 64-bit addresses for MSI to work on platforms with MSI
> doorbell above 32-bit address space.
>
> Signed-off-by: Vivian Wang <wangruikang@...as.ac.cn>
For the sound part:
Acked-by: Takashi Iwai <tiwai@...e.de>
thanks,
Takashi
>
> ---
>
> v2: Minor rewording. No code changes.
>
> checkpatch complains about the comment include/linux/pci.h, which I have
> formatted similarly with other comments in the vicinity.
> ---
> arch/powerpc/platforms/powernv/pci-ioda.c | 2 +-
> arch/powerpc/platforms/pseries/msi.c | 4 ++--
> drivers/gpu/drm/radeon/radeon_irq_kms.c | 2 +-
> drivers/net/ethernet/pensando/ionic/ionic_bus_pci.c | 2 +-
> drivers/pci/msi/msi.c | 2 +-
> drivers/pci/msi/pcidev_msi.c | 2 +-
> drivers/pci/probe.c | 7 +++++++
> include/linux/pci.h | 8 +++++++-
> sound/hda/controllers/intel.c | 2 +-
> 9 files changed, 22 insertions(+), 9 deletions(-)
>
> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
> index b0c1d9d16fb5..1c78fdfb7b03 100644
> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
> +++ b/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 */
> diff --git a/arch/powerpc/platforms/pseries/msi.c b/arch/powerpc/platforms/pseries/msi.c
> index a82aaa786e9e..7473c7ca1db0 100644
> --- a/arch/powerpc/platforms/pseries/msi.c
> +++ b/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 @@ static int rtas_prepare_msi_irqs(struct pci_dev *pdev, int nvec_in, int type,
> 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);
> 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 34d664139f48..48f5f03d1479 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));
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 864775651c6f..0fe32fef0331 100644
> --- a/include/linux/pci.h
> +++ b/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 */
> diff --git a/sound/hda/controllers/intel.c b/sound/hda/controllers/intel.c
> index 1e8e3d61291a..c9542ebdf7e2 100644
> --- a/sound/hda/controllers/intel.c
> +++ b/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);
>
> --
> 2.52.0
>
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