Re: [PATCH v1 2/8] x86/xen: simplify xen_oldmem_pfn_is_ram()
On 29.09.21 16:22, Boris Ostrovsky wrote:
On 9/29/21 5:03 AM, David Hildenbrand wrote:
On 29.09.21 10:45, David Hildenbrand wrote:
Can we go one step further and do
@@ -20,24 +20,11 @@ static int xen_oldmem_pfn_is_ram(unsigned long pfn)
struct xen_hvm_get_mem_type a = {
.domid = DOMID_SELF,
.pfn = pfn,
+ .mem_type = HVMMEM_ram_rw,
};
- int ram;
- if (HYPERVISOR_hvm_op(HVMOP_get_mem_type, ))
- return -ENXIO;
-
- switch (a.mem_type) {
- case HVMMEM_mmio_dm:
- ram = 0;
- break;
- case HVMMEM_ram_rw:
- case HVMMEM_ram_ro:
- default:
- ram = 1;
- break;
- }
-
- return ram;
+ HYPERVISOR_hvm_op(HVMOP_get_mem_type, );
+ return a.mem_type != HVMMEM_mmio_dm;
I was actually thinking of asking you to add another patch with pr_warn_once()
here (and print error code as well). This call failing is indication of
something going quite wrong and it would be good to know about this.
Will include a patch in v2, thanks!
--
Thanks,
David / dhildenb
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Re: [PATCH v1 2/8] x86/xen: simplify xen_oldmem_pfn_is_ram()
On 9/29/21 5:03 AM, David Hildenbrand wrote:
> On 29.09.21 10:45, David Hildenbrand wrote:
>>>
>> Can we go one step further and do
>>
>>
>> @@ -20,24 +20,11 @@ static int xen_oldmem_pfn_is_ram(unsigned long pfn)
>> struct xen_hvm_get_mem_type a = {
>> .domid = DOMID_SELF,
>> .pfn = pfn,
>> + .mem_type = HVMMEM_ram_rw,
>> };
>> - int ram;
>> - if (HYPERVISOR_hvm_op(HVMOP_get_mem_type, ))
>> - return -ENXIO;
>> -
>> - switch (a.mem_type) {
>> - case HVMMEM_mmio_dm:
>> - ram = 0;
>> - break;
>> - case HVMMEM_ram_rw:
>> - case HVMMEM_ram_ro:
>> - default:
>> - ram = 1;
>> - break;
>> - }
>> -
>> - return ram;
>> + HYPERVISOR_hvm_op(HVMOP_get_mem_type, );
>> + return a.mem_type != HVMMEM_mmio_dm;
I was actually thinking of asking you to add another patch with pr_warn_once()
here (and print error code as well). This call failing is indication of
something going quite wrong and it would be good to know about this.
>> }
>> #endif
>>
>>
>> Assuming that if HYPERVISOR_hvm_op() fails that
>> .mem_type is not set to HVMMEM_mmio_dm.
I don't think we can assume that argument described as OUT in the ABI will not
be clobbered in case of error
>>
>
> Okay we can't, due to "__must_check" ...
so this is a good thing ;-)
-boris
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Re: [PATCH v1 2/8] x86/xen: simplify xen_oldmem_pfn_is_ram()
On 29.09.21 10:45, David Hildenbrand wrote:
How about
return a.mem_type != HVMMEM_mmio_dm;
Ha, how could I have missed that :)
Result should be promoted to int and this has added benefit of not requiring
changes in patch 4.
Can we go one step further and do
@@ -20,24 +20,11 @@ static int xen_oldmem_pfn_is_ram(unsigned long pfn)
struct xen_hvm_get_mem_type a = {
.domid = DOMID_SELF,
.pfn = pfn,
+ .mem_type = HVMMEM_ram_rw,
};
- int ram;
- if (HYPERVISOR_hvm_op(HVMOP_get_mem_type, ))
- return -ENXIO;
-
- switch (a.mem_type) {
- case HVMMEM_mmio_dm:
- ram = 0;
- break;
- case HVMMEM_ram_rw:
- case HVMMEM_ram_ro:
- default:
- ram = 1;
- break;
- }
-
- return ram;
+ HYPERVISOR_hvm_op(HVMOP_get_mem_type, );
+ return a.mem_type != HVMMEM_mmio_dm;
}
#endif
Assuming that if HYPERVISOR_hvm_op() fails that
.mem_type is not set to HVMMEM_mmio_dm.
Okay we can't, due to "__must_check" ...
--
Thanks,
David / dhildenb
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Re: [PATCH v1 2/8] x86/xen: simplify xen_oldmem_pfn_is_ram()
How about
return a.mem_type != HVMMEM_mmio_dm;
Ha, how could I have missed that :)
Result should be promoted to int and this has added benefit of not requiring
changes in patch 4.
Can we go one step further and do
@@ -20,24 +20,11 @@ static int xen_oldmem_pfn_is_ram(unsigned long pfn)
struct xen_hvm_get_mem_type a = {
.domid = DOMID_SELF,
.pfn = pfn,
+ .mem_type = HVMMEM_ram_rw,
};
- int ram;
- if (HYPERVISOR_hvm_op(HVMOP_get_mem_type, ))
- return -ENXIO;
-
- switch (a.mem_type) {
- case HVMMEM_mmio_dm:
- ram = 0;
- break;
- case HVMMEM_ram_rw:
- case HVMMEM_ram_ro:
- default:
- ram = 1;
- break;
- }
-
- return ram;
+ HYPERVISOR_hvm_op(HVMOP_get_mem_type, );
+ return a.mem_type != HVMMEM_mmio_dm;
}
#endif
Assuming that if HYPERVISOR_hvm_op() fails that
.mem_type is not set to HVMMEM_mmio_dm.
--
Thanks,
David / dhildenb
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Re: [PATCH v1 2/8] x86/xen: simplify xen_oldmem_pfn_is_ram()
On 9/28/21 2:22 PM, David Hildenbrand wrote:
> Let's simplify return handling.
>
> Signed-off-by: David Hildenbrand
> ---
> arch/x86/xen/mmu_hvm.c | 11 ++-
> 1 file changed, 2 insertions(+), 9 deletions(-)
>
> diff --git a/arch/x86/xen/mmu_hvm.c b/arch/x86/xen/mmu_hvm.c
> index b242d1f4b426..eb61622df75b 100644
> --- a/arch/x86/xen/mmu_hvm.c
> +++ b/arch/x86/xen/mmu_hvm.c
> @@ -21,23 +21,16 @@ static int xen_oldmem_pfn_is_ram(unsigned long pfn)
> .domid = DOMID_SELF,
> .pfn = pfn,
> };
> - int ram;
>
> if (HYPERVISOR_hvm_op(HVMOP_get_mem_type, ))
> return -ENXIO;
>
> switch (a.mem_type) {
> case HVMMEM_mmio_dm:
> - ram = 0;
> - break;
> - case HVMMEM_ram_rw:
> - case HVMMEM_ram_ro:
> + return 0;
> default:
> - ram = 1;
> - break;
> + return 1;
> }
> -
> - return ram;
> }
> #endif
>
How about
return a.mem_type != HVMMEM_mmio_dm;
Result should be promoted to int and this has added benefit of not requiring
changes in patch 4.
-boris
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