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

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Message-ID: <8e0cae73-3ca0-47a8-8ac7-aa8edba3e0f9@iscas.ac.cn>
Date: Thu, 22 Jan 2026 18:22:54 +0800
From: Vivian Wang <wangruikang@...as.ac.cn>
To: Bjorn Helgaas <helgaas@...nel.org>
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()

On 1/22/26 07:38, Bjorn Helgaas wrote:
> [+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.

Thanks for catching. I misunderstood the purpose of the original message
formatting.

I will fix this in v3.

Vivian "dramforever" Wang