[Xen-devel] Re: [PATCH] x86/cpa: make sure cpa is safe to call in lazy mmu mode

[Ingo Molnar <mingo@xxxxxxx>]

* Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:

> [ Ingo, this needs to go upstream and -stable. -J ]
>
> commit 2193cee29f66b873b9f8ac2cebb2c7b755ec73a3
> Author: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
> Date:   Tue Feb 10 14:15:52 2009 -0800
>
>    x86/cpa: make sure cpa is safe to call in lazy mmu mode
>       Impact: fix race leading to crash under KVM and Xen
>
>    The CPA code may be called while we're in lazy mmu update mode - for
>    example, when using DEBUG_PAGE_ALLOC and doing a slab allocation
>    in an interrupt handler which interrupted a lazy mmu update.  In this
>    case, the in-memory pagetable state may be out of date due to pending
>    queued updates.  We need to flush any pending updates before inspecting
>    the page table.  Similarly, we must explicitly flush any modifications
>    CPA may have made (which comes down to flushing queued operations when
>    flushing the TLB).
>       Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
>    Acked-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>

applied to tip:x86/urgent, thanks Jeremy!

        Ingo

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