Re: [PATCH v9 5/8] vpci: Refactor vpci_remove_register to remove matched registers

["Chen, Jiqian" <Jiqian.Chen@xxxxxxx>]

On 2025/7/30 19:23, Andrew Cooper wrote:
> On 28/07/2025 6:03 am, Jiqian Chen wrote:
>> vpci_remove_register() only supports removing a register in a time,
>> but the follow-on changes need to remove all registers within a range.
>> So, refactor it to support removing all registers in a given region.
>>
>> And it is no issue to remove a non exist register, so remove the
>> __must_check prefix.
>>
>> Signed-off-by: Jiqian Chen <Jiqian.Chen@xxxxxxx>
>> Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> 
> Bisection says this causes an assertion failure in the unit test.
> 
> Running /usr/lib/xen/tests/test_vpci
> Assertion failed: vpci_remove_registers(test_pdev.vpci, 16, 2) (main.c:
> main: 407)
> FAILED: /usr/lib/xen/tests/test_vpci
Thanks Andrew.
This is because new function vpci_remove_registers() removes all registers 
inside (offset, offset + size) and returns failure when overlap happens.
For tools/tests/vpci/main.c, there are layout:
     *
     * 32    24    16     8     0
     *  +------+------+------+------+
     *  |            r0             | 0
     *  +------+------+------+------+
     *  |  r7  |  r6  |  r5  |//////| 4
     *  +------+------+------+------|
     *  |///////////////////////////| 8
     *  +-------------+-------------+
     *  |/////////////|    r12      | 12
     *  +------+------+------+------+
     *  |r16[3]|r16[2]|r16[1]|r16[0]| 16
     *  +------+------+------+------+
     *  |    r20[1]   |    r20[0]   | 20
     *  +-------------+-------------|
     *  |            r24            | 24
     *  +------+------+------+------+
     *  |//////|  r30 |//////|  r28 | 28
     *  +------+------+------+------+
     *  |rsvdz |rsvdp | rw1c |  ro  | 32
     *  +------+------+------+------+
     *
As for the last three test cases:
    VPCI_REMOVE_INVALID_REG(20, 1);
    This can success as this overlap with r20[0]
    VPCI_REMOVE_INVALID_REG(16, 2);
    VPCI_REMOVE_INVALID_REG(30, 2);
    These two fail as there are r16[0], r16[1] and r30 inside them, so remove 
success and test cases fail.
So, I think we need to change these two test cases to match the new function's 
logic, like:
VPCI_REMOVE_INVALID_REG(0, 2);
VPCI_REMOVE_INVALID_REG(2, 2);
Or delete them directly.

Hi Roger, what's your opinion?

> 
> Full logs, not that they're of any more help:
> 
> https://gitlab.com/xen-project/hardware/xen-staging/-/pipelines/1956817587
> 
> ~Andrew

-- 
Best regards,
Jiqian Chen.