netdev - Re: [PATCH v2 2/4] PCI/MSI: Check msi_addr_mask in msi_verify

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Message-ID: <20260121233804.GA1221537@bhelgaas>
Date: Wed, 21 Jan 2026 17:38:04 -0600
From: Bjorn Helgaas <helgaas@...nel.org>
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,
	Thomas Gleixner <tglx@...nel.org>
Subject: Re: [PATCH v2 2/4] PCI/MSI: Check msi_addr_mask in
 msi_verify_entries()

[+cc Thomas, thread at https://lore.kernel.org/r/20260121-pci-msi-addr-mask-v2-0-f42593168989@iscas.ac.cn]

On Wed, Jan 21, 2026 at 11:49:38AM +0800, Vivian Wang wrote:
> Instead of a 32-bit/64-bit dichotomy, check the MSI address against
> msi_addr_mask.
> 
> This allows platforms with MSI doorbell above 32-bit address space to
> work with devices without full 64-bit MSI address support, as long as
> the doorbell is within addressable range of MSI of the device.
> 
> Signed-off-by: Vivian Wang <wangruikang@...as.ac.cn>
> 
> ---
> v2: No changes
> ---
>  drivers/pci/msi/msi.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/msi/msi.c b/drivers/pci/msi/msi.c
> index 48f5f03d1479..2ecbcd6c436a 100644
> --- a/drivers/pci/msi/msi.c
> +++ b/drivers/pci/msi/msi.c
> @@ -321,14 +321,17 @@ static int msi_setup_msi_desc(struct pci_dev *dev, int nvec,
>  static int msi_verify_entries(struct pci_dev *dev)
>  {
>  	struct msi_desc *entry;
> +	u64 address;
>  
>  	if (dev->msi_addr_mask == DMA_BIT_MASK(64))
>  		return 0;
>  
>  	msi_for_each_desc(entry, &dev->dev, MSI_DESC_ALL) {
> -		if (entry->msg.address_hi) {
> -			pci_err(dev, "arch assigned 64-bit MSI address %#x%08x but device only supports 32 bits\n",
> -				entry->msg.address_hi, entry->msg.address_lo);
> +		address = (u64)entry->msg.address_hi << 32 |
> +			  entry->msg.address_lo;
> +		if (address & ~dev->msi_addr_mask) {
> +			pci_err(dev, "arch assigned 64-bit MSI address %llx above device MSI address mask %llx\n",

Use %#llx so it's clear these addresses are hex.  The previous message
did that, not sure why you dropped it.

> +				address, dev->msi_addr_mask);
>  			break;
>  		}
>  	}
> 
> -- 
> 2.52.0
>