From: Wei Liu <wei.liu@kernel.org>
To: Jeffrey Hugo <quic_jhugo@quicinc.com>
Cc: kys@microsoft.com, haiyangz@microsoft.com,
sthemmin@microsoft.com, wei.liu@kernel.org, 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 14:41:24 +0000 [thread overview]
Message-ID: <20220511144124.rj7inq6zy6bgbii4@liuwe-devbox-debian-v2> (raw)
In-Reply-To: <1652132902-27109-1-git-send-email-quic_jhugo@quicinc.com>
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.
next prev parent reply other threads:[~2022-05-11 14:41 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 [this message]
2022-05-11 14:47 ` Jeffrey Hugo
2022-05-11 15:19 ` Wei Liu
2022-05-11 15:21 ` Jeffrey Hugo
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