Re: [edk2-devel] [RFC/RFT PATCH] OvmfPkg/IoMmuDxe: don't rely on TPLs for re-entrancy

["Gerd Hoffmann" <kraxel@redhat.com>]

On Thu, Jul 20, 2023 at 03:45:57PM +0200, Ard Biesheuvel wrote:
> Instead of relying on raising the TPL to protect the critical sections
> that manipulate the global bitmask that keeps track of bounce buffer
> allocations, use compare-and-exchange to manage the global variable, and
> tweak the logic to line up with that.
> 
> Given that IoMmuDxe implements a singleton protocol that is shared
> between multiple drivers, and considering the elaborate and confusing
> requirements in the UEFP spec regarding TPL levels at which protocol
> methods may be invoked, not relying on TPL levels at all is a more
> robust approach in this case.
> 
> Cc: Gerd Hoffmann <kraxel@redhat.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Michael Brown <mcb30@ipxe.org>
> Link: https://bugzilla.redhat.com/show_bug.cgi?id=2211060
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

Looks good to me.

What is the status?  Merged?  Or waiting for testing still?  If so I can
create a test build with the patch and ask our QE department to check
it.

take care,
  Gerd



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