Re: [PATCH 1/2] PCI: hv: Reuse existing ITRE allocation in compose_msi_msg()

On 5/9/2022 5:13 PM, Dexuan Cui wrote:

quoted

From: Jeffrey Hugo <redacted>
Sent: Monday, May 9, 2022 2:48 PM
Subject: [PATCH 1/2] PCI: hv: Reuse existing ITRE allocation in

s/ITRE/IRTE. I suppose Wei can help fix this without a v2 :-)

Thanks for the review.

I have no problem sending out a V2.  Especially since you pointed out my 
mistakes on both patches.  I'll wait a little bit for any additional 
feedback, and then send out a V2.

quoted

compose_msi_msg()
...
Currently if compose_msi_msg() is called multiple times, it will free any
previous ITRE allocation, and generate a new allocation.  While nothing
prevents this from occurring, it is extranious when Linux could just reuse

s/extranious/extraneous

quoted

the existing allocation and avoid a bunch of overhead.

However, when future ITRE allocations operate on blocks of MSIs instead of

s/ITRE/IRTE

quoted

a single line, freeing the allocation will impact all of the lines.  This
could cause an issue where an allocation of N MSIs occurs, then some of
the lines are retargeted, and finally the allocation is freed/reallocated.
The freeing of the allocation removes all of the configuration for the
entire block, which requires all the lines to be retargeted, which might
not happen since some lines might already be unmasked/active.

Signed-off-by: Jeffrey Hugo <redacted>

Reviewed-by: Dexuan Cui <decui@microsoft.com>
Tested-by: Dexuan Cui <decui@microsoft.com>