From: Jeffrey Hugo <quic_jhugo@quicinc.com>
To: Wei Liu <wei.liu@kernel.org>
Cc: <kys@microsoft.com>, <haiyangz@microsoft.com>,
<sthemmin@microsoft.com>, <decui@microsoft.com>,
<lorenzo.pieralisi@arm.com>, <robh@kernel.org>, <kw@linux.com>,
<bhelgaas@google.com>, <jakeo@microsoft.com>,
<dazhan@microsoft.com>, <linux-hyperv@vger.kernel.org>,
<linux-pci@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/2] hyperv compose_msi_msg fixups
Date: Wed, 11 May 2022 08:47:23 -0600 [thread overview]
Message-ID: <a0e60283-a448-650f-808e-a0080ae550f7@quicinc.com> (raw)
In-Reply-To: <20220511144124.rj7inq6zy6bgbii4@liuwe-devbox-debian-v2>
On 5/11/2022 8:41 AM, Wei Liu wrote:
> On Mon, May 09, 2022 at 03:48:20PM -0600, Jeffrey Hugo wrote:
>> While multi-MSI appears to work with pci-hyperv.c, there was a concern about
>> how linux was doing the ITRE allocations. Patch 2 addresses the concern.
>>
>> However, patch 2 exposed an issue with how compose_msi_msg() was freeing a
>> previous allocation when called for the Nth time. Imagine a driver using
>> pci_alloc_irq_vectors() to request 32 MSIs. This would cause compose_msi_msg()
>> to be called 32 times, once for each MSI. With patch 2, MSI0 would allocate
>> the ITREs needed, and MSI1-31 would use the cached information. Then the driver
>> uses request_irq() on MSI1-17. This would call compose_msi_msg() again on those
>> MSIs, which would again use the cached information. Then unmask() would be
>> called to retarget the MSIs to the right VCPU vectors. Finally, the driver
>> calls request_irq() on MSI0. This would call conpose_msi_msg(), which would
>> free the block of 32 MSIs, and allocate a new block. This would undo the
>> retarget of MSI1-17, and likely leave those MSIs targeting invalid VCPU vectors.
>> This is addressed by patch 1, which is introduced first to prevent a regression.
>>
>> Jeffrey Hugo (2):
>> PCI: hv: Reuse existing ITRE allocation in compose_msi_msg()
>> PCI: hv: Fix interrupt mapping for multi-MSI
>>
>
> Applied to hyperv-next. Thanks.
Huh? I thought you wanted a V2. I was intending on sending that out today.
-Jeff
next prev parent reply other threads:[~2022-05-11 14:47 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-09 21:48 [PATCH 0/2] hyperv compose_msi_msg fixups Jeffrey Hugo
2022-05-09 21:48 ` [PATCH 1/2] PCI: hv: Reuse existing ITRE allocation in compose_msi_msg() Jeffrey Hugo
2022-05-09 23:13 ` Dexuan Cui
2022-05-10 2:29 ` Jeffrey Hugo
2022-05-10 10:52 ` Wei Liu
2022-05-09 21:48 ` [PATCH 2/2] PCI: hv: Fix interrupt mapping for multi-MSI Jeffrey Hugo
2022-05-09 23:21 ` Dexuan Cui
2022-05-09 23:23 ` [PATCH 0/2] hyperv compose_msi_msg fixups Dexuan Cui
2022-05-10 2:31 ` Jeffrey Hugo
2022-05-10 18:13 ` Michael Kelley (LINUX)
2022-05-11 14:41 ` Wei Liu
2022-05-11 14:47 ` Jeffrey Hugo [this message]
2022-05-11 15:19 ` Wei Liu
2022-05-11 15:21 ` Jeffrey Hugo
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