From: Easwar Hariharan <easwar.hariharan@linux.microsoft.com>
To: Yuho Choi <oss.patchbox@gmail.com>
Cc: "Joerg Roedel (AMD)" <joro@8bytes.org>,
Will Deacon <will@kernel.org>, Wei Liu <wei.liu@kernel.org>,
easwar.hariharan@linux.microsoft.com,
Robin Murphy <robin.murphy@arm.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Dexuan Cui <decui@microsoft.com>,
Yu Zhang <zhangyu1@linux.microsoft.com>,
Jacob Pan <jacob.pan@linux.microsoft.com>,
Michael Kelley <mhklinux@outlook.com>,
Jason Gunthorpe <jgg@ziepe.ca>,
iommu@lists.linux.dev, linux-hyperv@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1] iommu/hyperv: Don't free a paging domain the hypervisor did not delete
Date: Thu, 5 Nov 2026 11:53:01 -0800 [thread overview]
Message-ID: <b321af97-a39e-4b26-9dfb-e47e5d1dc044@linux.microsoft.com> (raw)
In-Reply-To: <20261105192738.70664-2-oss.patchbox@gmail.com>
On 11/5/2026 11:27, Yuho Choi wrote:
> hv_iommu_paging_domain_free() frees all page-table pages with
> pt_iommu_deinit() and only then asks the hypervisor to delete the
> device domain that points at them. If HVCALL_DELETE_DEVICE_DOMAIN
> fails, hv_delete_device_domain() only logs the error, returns the
> domain ID to the IDA, and the domain is freed anyway.
>
> The hypervisor then keeps a device domain whose page tables have been
> freed and can be reused for anything. The ID is also handed out again
> by the next paging domain allocation, while the hypervisor still has a
> domain with that ID.
>
> Delete the domain before freeing its page tables, and keep the ID, the
> page tables and the domain if the hypervisor fails to delete it.
>
> Fixes: 2690d4156b51 ("iommu/hyperv: Add para-virtualized IOMMU support for Hyper-V guest")
> Signed-off-by: Yuho Choi <oss.patchbox@gmail.com>
> ---
> Compile-tested only (x86_64 with HYPERV and HYPERV_PVIOMMU,
> W=1); I have no Hyper-V guest with the para-virtualized IOMMU to test
> it on.
>
> drivers/iommu/hyperv/hv-iommu-guest.c | 17 +++++++++++++----
> 1 file changed, 13 insertions(+), 4 deletions(-)
>
Good catch!
Reviewed-by: Easwar Hariharan <easwar.hariharan@linux.microsoft.com>
next prev parent reply other threads:[~2026-11-05 19:53 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-05 19:27 Yuho Choi
2026-11-05 19:53 ` Easwar Hariharan [this message]
2026-11-05 20:31 ` Jason Gunthorpe
2026-11-05 22:14 ` Jacob Pan
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