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Re: [PATCH] intel-iommu: Set status bit after operation completed
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From: |
Peter Xu |
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Subject: |
Re: [PATCH] intel-iommu: Set status bit after operation completed |
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Date: |
Fri, 10 Mar 2023 09:29:04 -0500 |
On Fri, Mar 10, 2023 at 02:32:13AM +0000, Duan, Zhenzhong wrote:
> I think it may break with special designed guest OS,
> E.x: Imagine a guest write GCMD_REG and start a new thread to do further work.
> New thread find status bit in GTS_REG set and go ahead, but the address space
> switch
> may not finish yet if guest memory is big, which may trigger a potential race.
IMHO it's fine. For MMIO QEMU takes the BQL so if another thread reads the
status reg it should be serialized until the current vcpu finishes.
See prepare_mmio_access(). Thanks,
--
Peter Xu