[PATCH] lib/logic_pio: Fix overlap check for pio registery

[PATCH] lib/logic_pio: Fix overlap check for pio registery

[Jiahui Cen]

Since the [start, end) is a half-open interval, a range with the end equal
to the start of another range should not be considered as overlapped.

Signed-off-by: Jiahui Cen <cenjiahui@huawei.com>
---
 lib/logic_pio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/logic_pio.c b/lib/logic_pio.c
index f32fe481b492..445d611f1dc1 100644
--- a/lib/logic_pio.c
+++ b/lib/logic_pio.c
@@ -57,7 +57,7 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
 		    new_range->flags == LOGIC_PIO_CPU_MMIO) {
 			/* for MMIO ranges we need to check for overlap */
 			if (start >= range->hw_start + range->size ||
-			    end < range->hw_start) {
+			    end <= range->hw_start) {
 				mmio_end = range->io_start + range->size;
 			} else {
 				ret = -EFAULT;
-- 
2.28.0

Re: [PATCH] lib/logic_pio: Fix overlap check for pio registery

[John Garry]

On 18/12/2020 06:23, Jiahui Cen wrote:
> Since the [start, end) is a half-open interval, a range with the end equal
> to the start of another range should not be considered as overlapped.
> 
> Signed-off-by: Jiahui Cen <cenjiahui@huawei.com>
> ---
>   lib/logic_pio.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/logic_pio.c b/lib/logic_pio.c
> index f32fe481b492..445d611f1dc1 100644
> --- a/lib/logic_pio.c
> +++ b/lib/logic_pio.c
> @@ -57,7 +57,7 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
>   		    new_range->flags == LOGIC_PIO_CPU_MMIO) {
>   			/* for MMIO ranges we need to check for overlap */
>   			if (start >= range->hw_start + range->size ||
> -			    end < range->hw_start) {
> +			    end <= range->hw_start) {

It looks like your change is correct, but should not really have an 
impact in practice since:
a: BIOSes generally list ascending IO port CPU addresses
b. there is space between IO port CPU address regions

Have you seen a problem here?

Thanks,
John

Re: [PATCH] lib/logic_pio: Fix overlap check for pio registery

[Jiahui Cen]

Hi John,

On 2020/12/18 18:40, John Garry wrote:
> On 18/12/2020 06:23, Jiahui Cen wrote:
>> Since the [start, end) is a half-open interval, a range with the end equal
>> to the start of another range should not be considered as overlapped.
>>
>> Signed-off-by: Jiahui Cen <cenjiahui@huawei.com>
>> ---
>>   lib/logic_pio.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/lib/logic_pio.c b/lib/logic_pio.c
>> index f32fe481b492..445d611f1dc1 100644
>> --- a/lib/logic_pio.c
>> +++ b/lib/logic_pio.c
>> @@ -57,7 +57,7 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
>>               new_range->flags == LOGIC_PIO_CPU_MMIO) {
>>               /* for MMIO ranges we need to check for overlap */
>>               if (start >= range->hw_start + range->size ||
>> -                end < range->hw_start) {
>> +                end <= range->hw_start) {
> 
> It looks like your change is correct, but should not really have an impact in practice since:
> a: BIOSes generally list ascending IO port CPU addresses
> b. there is space between IO port CPU address regions
> 
> Have you seen a problem here?
> 

No serious problem. I found it just when I was working on adding support of
pci expander bridge for Arm in QEMU. I found the IO window of some extended
root bus could not be registered when I inserted the extended buses' _CRS
info into DSDT table in the x86 way, which does not sort the buses.

Though root buses should be sorted in QEMU, would it be better to accept
those non-ascending IO windows?

BTW, for b, it seems to be no space between IO windows of different root buses
generated by EDK2. Or maybe I missed something obvious.

Thanks,
Jiahui

Re: [PATCH] lib/logic_pio: Fix overlap check for pio registery

[John Garry]

On 21/12/2020 03:24, Jiahui Cen wrote:
> Hi John,
> 
> On 2020/12/18 18:40, John Garry wrote:
>> On 18/12/2020 06:23, Jiahui Cen wrote:
>>> Since the [start, end) is a half-open interval, a range with the end equal
>>> to the start of another range should not be considered as overlapped.
>>>
>>> Signed-off-by: Jiahui Cen<cenjiahui@huawei.com>
>>> ---
>>>    lib/logic_pio.c | 2 +-
>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/lib/logic_pio.c b/lib/logic_pio.c
>>> index f32fe481b492..445d611f1dc1 100644
>>> --- a/lib/logic_pio.c
>>> +++ b/lib/logic_pio.c
>>> @@ -57,7 +57,7 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
>>>                new_range->flags == LOGIC_PIO_CPU_MMIO) {
>>>                /* for MMIO ranges we need to check for overlap */
>>>                if (start >= range->hw_start + range->size ||
>>> -                end < range->hw_start) {
>>> +                end <= range->hw_start) {
>> It looks like your change is correct, but should not really have an impact in practice since:
>> a: BIOSes generally list ascending IO port CPU addresses
>> b. there is space between IO port CPU address regions
>>
>> Have you seen a problem here?
>>
> No serious problem. I found it just when I was working on adding support of
> pci expander bridge for Arm in QEMU. I found the IO window of some extended
> root bus could not be registered when I inserted the extended buses' _CRS
> info into DSDT table in the x86 way, which does not sort the buses.
> 
> Though root buses should be sorted in QEMU, would it be better to accept
> those non-ascending IO windows?
> 

ok, so it seems that you have seen a real problem, and this issue is not 
just detected by code analysis.

> BTW, for b, it seems to be no space between IO windows of different root buses
> generated by EDK2. Or maybe I missed something obvious.

I don't know about that. Anyway, your change looks ok.

Reviewed-by: John Garry <john.garry@huawei.com>

BTW, for your virt env, will there be requirement to unregister PCI MMIO 
ranges? Currently we don't see that in non-virt world.

Thanks,
John

Re: [PATCH] lib/logic_pio: Fix overlap check for pio registery

[Jiahui Cen]

Hi John,

On 2020/12/21 19:12, John Garry wrote:
> On 21/12/2020 03:24, Jiahui Cen wrote:
>> Hi John,
>>
>> On 2020/12/18 18:40, John Garry wrote:
>>> On 18/12/2020 06:23, Jiahui Cen wrote:
>>>> Since the [start, end) is a half-open interval, a range with the end equal
>>>> to the start of another range should not be considered as overlapped.
>>>>
>>>> Signed-off-by: Jiahui Cen<cenjiahui@huawei.com>
>>>> ---
>>>>    lib/logic_pio.c | 2 +-
>>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/lib/logic_pio.c b/lib/logic_pio.c
>>>> index f32fe481b492..445d611f1dc1 100644
>>>> --- a/lib/logic_pio.c
>>>> +++ b/lib/logic_pio.c
>>>> @@ -57,7 +57,7 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
>>>>                new_range->flags == LOGIC_PIO_CPU_MMIO) {
>>>>                /* for MMIO ranges we need to check for overlap */
>>>>                if (start >= range->hw_start + range->size ||
>>>> -                end < range->hw_start) {
>>>> +                end <= range->hw_start) {
>>> It looks like your change is correct, but should not really have an impact in practice since:
>>> a: BIOSes generally list ascending IO port CPU addresses
>>> b. there is space between IO port CPU address regions
>>>
>>> Have you seen a problem here?
>>>
>> No serious problem. I found it just when I was working on adding support of
>> pci expander bridge for Arm in QEMU. I found the IO window of some extended
>> root bus could not be registered when I inserted the extended buses' _CRS
>> info into DSDT table in the x86 way, which does not sort the buses.
>>
>> Though root buses should be sorted in QEMU, would it be better to accept
>> those non-ascending IO windows?
>>
> 
> ok, so it seems that you have seen a real problem, and this issue is not just detected by code analysis.
> 
>> BTW, for b, it seems to be no space between IO windows of different root buses
>> generated by EDK2. Or maybe I missed something obvious.
> 
> I don't know about that. Anyway, your change looks ok.
> 
> Reviewed-by: John Garry <john.garry@huawei.com>
> 
> BTW, for your virt env, will there be requirement to unregister PCI MMIO ranges? Currently we don't see that in non-virt world.
> 

Thanks for your review.

And currently there is no such a requirement in my virt env.

Thanks,
Jiahui

Re: [PATCH] lib/logic_pio: Fix overlap check for pio registery

[John Garry]

On 21/12/2020 13:04, Jiahui Cen wrote:
>> On 21/12/2020 03:24, Jiahui Cen wrote:
>>> Hi John,
>>>
>>> On 2020/12/18 18:40, John Garry wrote:
>>>> On 18/12/2020 06:23, Jiahui Cen wrote:
>>>>> Since the [start, end) is a half-open interval, a range with the end equal
>>>>> to the start of another range should not be considered as overlapped.
>>>>>
>>>>> Signed-off-by: Jiahui Cen<cenjiahui@huawei.com>
>>>>> ---
>>>>>     lib/logic_pio.c | 2 +-
>>>>>     1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/lib/logic_pio.c b/lib/logic_pio.c
>>>>> index f32fe481b492..445d611f1dc1 100644
>>>>> --- a/lib/logic_pio.c
>>>>> +++ b/lib/logic_pio.c
>>>>> @@ -57,7 +57,7 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
>>>>>                 new_range->flags == LOGIC_PIO_CPU_MMIO) {
>>>>>                 /* for MMIO ranges we need to check for overlap */
>>>>>                 if (start >= range->hw_start + range->size ||
>>>>> -                end < range->hw_start) {
>>>>> +                end <= range->hw_start) {
>>>> It looks like your change is correct, but should not really have an impact in practice since:
>>>> a: BIOSes generally list ascending IO port CPU addresses
>>>> b. there is space between IO port CPU address regions
>>>>
>>>> Have you seen a problem here?
>>>>
>>> No serious problem. I found it just when I was working on adding support of
>>> pci expander bridge for Arm in QEMU. I found the IO window of some extended
>>> root bus could not be registered when I inserted the extended buses' _CRS
>>> info into DSDT table in the x86 way, which does not sort the buses.
>>>
>>> Though root buses should be sorted in QEMU, would it be better to accept
>>> those non-ascending IO windows?
>>>
>> ok, so it seems that you have seen a real problem, and this issue is not just detected by code analysis.
>>
>>> BTW, for b, it seems to be no space between IO windows of different root buses
>>> generated by EDK2. Or maybe I missed something obvious.
>> I don't know about that. Anyway, your change looks ok.
>>
>> Reviewed-by: John Garry<john.garry@huawei.com>
>>
>> BTW, for your virt env, will there be requirement to unregister PCI MMIO ranges? Currently we don't see that in non-virt world.
>>
> Thanks for your review.
> 
> And currently there is no such a requirement in my virt env.
> 

I am not sure what happened to this patch, but I plan on sending some 
patches in this area soon - do you want me to include this one?

Thanks,
John

Re: [PATCH] lib/logic_pio: Fix overlap check for pio registery

[Jiahui Cen]

Hi John,

On 2021/1/15 18:10, John Garry wrote:
> On 21/12/2020 13:04, Jiahui Cen wrote:
>>> On 21/12/2020 03:24, Jiahui Cen wrote:
>>>> Hi John,
>>>>
>>>> On 2020/12/18 18:40, John Garry wrote:
>>>>> On 18/12/2020 06:23, Jiahui Cen wrote:
>>>>>> Since the [start, end) is a half-open interval, a range with the end equal
>>>>>> to the start of another range should not be considered as overlapped.
>>>>>>
>>>>>> Signed-off-by: Jiahui Cen<cenjiahui@huawei.com>
>>>>>> ---
>>>>>>     lib/logic_pio.c | 2 +-
>>>>>>     1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>>
>>>>>> diff --git a/lib/logic_pio.c b/lib/logic_pio.c
>>>>>> index f32fe481b492..445d611f1dc1 100644
>>>>>> --- a/lib/logic_pio.c
>>>>>> +++ b/lib/logic_pio.c
>>>>>> @@ -57,7 +57,7 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
>>>>>>                 new_range->flags == LOGIC_PIO_CPU_MMIO) {
>>>>>>                 /* for MMIO ranges we need to check for overlap */
>>>>>>                 if (start >= range->hw_start + range->size ||
>>>>>> -                end < range->hw_start) {
>>>>>> +                end <= range->hw_start) {
>>>>> It looks like your change is correct, but should not really have an impact in practice since:
>>>>> a: BIOSes generally list ascending IO port CPU addresses
>>>>> b. there is space between IO port CPU address regions
>>>>>
>>>>> Have you seen a problem here?
>>>>>
>>>> No serious problem. I found it just when I was working on adding support of
>>>> pci expander bridge for Arm in QEMU. I found the IO window of some extended
>>>> root bus could not be registered when I inserted the extended buses' _CRS
>>>> info into DSDT table in the x86 way, which does not sort the buses.
>>>>
>>>> Though root buses should be sorted in QEMU, would it be better to accept
>>>> those non-ascending IO windows?
>>>>
>>> ok, so it seems that you have seen a real problem, and this issue is not just detected by code analysis.
>>>
>>>> BTW, for b, it seems to be no space between IO windows of different root buses
>>>> generated by EDK2. Or maybe I missed something obvious.
>>> I don't know about that. Anyway, your change looks ok.
>>>
>>> Reviewed-by: John Garry<john.garry@huawei.com>
>>>
>>> BTW, for your virt env, will there be requirement to unregister PCI MMIO ranges? Currently we don't see that in non-virt world.
>>>
>> Thanks for your review.
>>
>> And currently there is no such a requirement in my virt env.
>>
> 
> I am not sure what happened to this patch, but I plan on sending some patches in this area soon - do you want me to include this one?
> 

Sorry for replying late. It's appreciated if you can include this patch.

Thanks!
Jiahui

> Thanks,
> John
> 
> .

Re: [PATCH] lib/logic_pio: Fix overlap check for pio registery

[John Garry]

On 18/01/2021 01:27, Jiahui Cen wrote:

+

Hi Arnd, xu wei,

Any chance we could pick up this patch via arm-soc tree?

The series which I originally included in, below, is stalled a bit.

Thanks,
John

https://lore.kernel.org/lkml/1610729929-188490-1-git-send-email-john.garry@huawei.com/

> Hi John,
> 
> On 2021/1/15 18:10, John Garry wrote:
>> On 21/12/2020 13:04, Jiahui Cen wrote:
>>>> On 21/12/2020 03:24, Jiahui Cen wrote:
>>>>> Hi John,
>>>>>
>>>>> On 2020/12/18 18:40, John Garry wrote:
>>>>>> On 18/12/2020 06:23, Jiahui Cen wrote:
>>>>>>> Since the [start, end) is a half-open interval, a range with the end equal
>>>>>>> to the start of another range should not be considered as overlapped.
>>>>>>>
>>>>>>> Signed-off-by: Jiahui Cen<cenjiahui@huawei.com>
>>>>>>> ---
>>>>>>>      lib/logic_pio.c | 2 +-
>>>>>>>      1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>>>
>>>>>>> diff --git a/lib/logic_pio.c b/lib/logic_pio.c
>>>>>>> index f32fe481b492..445d611f1dc1 100644
>>>>>>> --- a/lib/logic_pio.c
>>>>>>> +++ b/lib/logic_pio.c
>>>>>>> @@ -57,7 +57,7 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
>>>>>>>                  new_range->flags == LOGIC_PIO_CPU_MMIO) {
>>>>>>>                  /* for MMIO ranges we need to check for overlap */
>>>>>>>                  if (start >= range->hw_start + range->size ||
>>>>>>> -                end < range->hw_start) {
>>>>>>> +                end <= range->hw_start) {
>>>>>> It looks like your change is correct, but should not really have an impact in practice since:
>>>>>> a: BIOSes generally list ascending IO port CPU addresses
>>>>>> b. there is space between IO port CPU address regions
>>>>>>
>>>>>> Have you seen a problem here?
>>>>>>
>>>>> No serious problem. I found it just when I was working on adding support of
>>>>> pci expander bridge for Arm in QEMU. I found the IO window of some extended
>>>>> root bus could not be registered when I inserted the extended buses' _CRS
>>>>> info into DSDT table in the x86 way, which does not sort the buses.
>>>>>
>>>>> Though root buses should be sorted in QEMU, would it be better to accept
>>>>> those non-ascending IO windows?
>>>>>
>>>> ok, so it seems that you have seen a real problem, and this issue is not just detected by code analysis.
>>>>
>>>>> BTW, for b, it seems to be no space between IO windows of different root buses
>>>>> generated by EDK2. Or maybe I missed something obvious.
>>>> I don't know about that. Anyway, your change looks ok.
>>>>
>>>> Reviewed-by: John Garry<john.garry@huawei.com>
>>>>
>>>> BTW, for your virt env, will there be requirement to unregister PCI MMIO ranges? Currently we don't see that in non-virt world.
>>>>
>>> Thanks for your review.
>>>
>>> And currently there is no such a requirement in my virt env.
>>>
>>
>> I am not sure what happened to this patch, but I plan on sending some patches in this area soon - do you want me to include this one?
>>
> 
> Sorry for replying late. It's appreciated if you can include this patch.
> 
> Thanks!
> Jiahui
> 
>> Thanks,
>> John
>>
>> .
> .
>