* [PATCH] KVM: s390: mark sie block as 512 byte aligned
@ 2020-03-11 8:33 Christian Borntraeger
2020-03-11 8:41 ` David Hildenbrand
2020-03-16 12:10 ` Claudio Imbrenda
0 siblings, 2 replies; 6+ messages in thread
From: Christian Borntraeger @ 2020-03-11 8:33 UTC (permalink / raw)
To: Janosch Frank
Cc: KVM, Cornelia Huck, Christian Borntraeger, David Hildenbrand,
linux-s390, Thomas Huth
The sie block must be aligned to 512 bytes. Mark it as such.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
arch/s390/include/asm/kvm_host.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 0ea82152d2f7..2d50f6c432e2 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -344,7 +344,7 @@ struct kvm_s390_sie_block {
__u64 itdba; /* 0x01e8 */
__u64 riccbd; /* 0x01f0 */
__u64 gvrd; /* 0x01f8 */
-} __attribute__((packed));
+} __packed __aligned(512);
struct kvm_s390_itdb {
__u8 data[256];
--
2.24.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] KVM: s390: mark sie block as 512 byte aligned
2020-03-11 8:33 [PATCH] KVM: s390: mark sie block as 512 byte aligned Christian Borntraeger
@ 2020-03-11 8:41 ` David Hildenbrand
2020-03-11 10:37 ` Christian Borntraeger
2020-03-16 12:10 ` Claudio Imbrenda
1 sibling, 1 reply; 6+ messages in thread
From: David Hildenbrand @ 2020-03-11 8:41 UTC (permalink / raw)
To: Christian Borntraeger, Janosch Frank
Cc: KVM, Cornelia Huck, linux-s390, Thomas Huth
On 11.03.20 09:33, Christian Borntraeger wrote:
> The sie block must be aligned to 512 bytes. Mark it as such.
>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
> arch/s390/include/asm/kvm_host.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
> index 0ea82152d2f7..2d50f6c432e2 100644
> --- a/arch/s390/include/asm/kvm_host.h
> +++ b/arch/s390/include/asm/kvm_host.h
> @@ -344,7 +344,7 @@ struct kvm_s390_sie_block {
> __u64 itdba; /* 0x01e8 */
> __u64 riccbd; /* 0x01f0 */
> __u64 gvrd; /* 0x01f8 */
> -} __attribute__((packed));
> +} __packed __aligned(512);
>
I guess there is no change in the code/behavior, because we always place
into well defined spots within a page.
Reviewed-by: David Hildenbrand <david@redhat.com>
--
Thanks,
David / dhildenb
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] KVM: s390: mark sie block as 512 byte aligned
2020-03-11 8:41 ` David Hildenbrand
@ 2020-03-11 10:37 ` Christian Borntraeger
0 siblings, 0 replies; 6+ messages in thread
From: Christian Borntraeger @ 2020-03-11 10:37 UTC (permalink / raw)
To: David Hildenbrand, Janosch Frank
Cc: KVM, Cornelia Huck, linux-s390, Thomas Huth
On 11.03.20 09:41, David Hildenbrand wrote:
> On 11.03.20 09:33, Christian Borntraeger wrote:
>> The sie block must be aligned to 512 bytes. Mark it as such.
>>
>> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
>> ---
>> arch/s390/include/asm/kvm_host.h | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
>> index 0ea82152d2f7..2d50f6c432e2 100644
>> --- a/arch/s390/include/asm/kvm_host.h
>> +++ b/arch/s390/include/asm/kvm_host.h
>> @@ -344,7 +344,7 @@ struct kvm_s390_sie_block {
>> __u64 itdba; /* 0x01e8 */
>> __u64 riccbd; /* 0x01f0 */
>> __u64 gvrd; /* 0x01f8 */
>> -} __attribute__((packed));
>> +} __packed __aligned(512);
>>
>
> I guess there is no change in the code/behavior, because we always place
> into well defined spots within a page.
In theory gcc can generate code that relies on that alignment. For example
load relative long requires double word alignment. Or some atomic instructions.
This could - in theory - generate better code.
>
> Reviewed-by: David Hildenbrand <david@redhat.com>
>
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] KVM: s390: mark sie block as 512 byte aligned
2020-03-11 8:33 [PATCH] KVM: s390: mark sie block as 512 byte aligned Christian Borntraeger
2020-03-11 8:41 ` David Hildenbrand
@ 2020-03-16 12:10 ` Claudio Imbrenda
2020-03-16 12:11 ` David Hildenbrand
1 sibling, 1 reply; 6+ messages in thread
From: Claudio Imbrenda @ 2020-03-16 12:10 UTC (permalink / raw)
To: Christian Borntraeger
Cc: Janosch Frank, KVM, Cornelia Huck, David Hildenbrand, linux-s390,
Thomas Huth
On Wed, 11 Mar 2020 09:33:04 +0100
Christian Borntraeger <borntraeger@de.ibm.com> wrote:
> The sie block must be aligned to 512 bytes. Mark it as such.
>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
> arch/s390/include/asm/kvm_host.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/s390/include/asm/kvm_host.h
> b/arch/s390/include/asm/kvm_host.h index 0ea82152d2f7..2d50f6c432e2
> 100644 --- a/arch/s390/include/asm/kvm_host.h
> +++ b/arch/s390/include/asm/kvm_host.h
> @@ -344,7 +344,7 @@ struct kvm_s390_sie_block {
> __u64 itdba; /* 0x01e8 */
> __u64 riccbd; /* 0x01f0 */
> __u64 gvrd; /* 0x01f8 */
> -} __attribute__((packed));
> +} __packed __aligned(512);
>
> struct kvm_s390_itdb {
> __u8 data[256];
I agree with the addition of aligned, but did you really have to remove
packed? it makes me a little uncomfortable.
do we have any compile-time assertions that the size of the block will
be the one we expect?
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] KVM: s390: mark sie block as 512 byte aligned
2020-03-16 12:10 ` Claudio Imbrenda
@ 2020-03-16 12:11 ` David Hildenbrand
2020-03-16 14:22 ` Claudio Imbrenda
0 siblings, 1 reply; 6+ messages in thread
From: David Hildenbrand @ 2020-03-16 12:11 UTC (permalink / raw)
To: Claudio Imbrenda, Christian Borntraeger
Cc: Janosch Frank, KVM, Cornelia Huck, linux-s390, Thomas Huth
On 16.03.20 13:10, Claudio Imbrenda wrote:
> On Wed, 11 Mar 2020 09:33:04 +0100
> Christian Borntraeger <borntraeger@de.ibm.com> wrote:
>
>> The sie block must be aligned to 512 bytes. Mark it as such.
>>
>> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
>> ---
>> arch/s390/include/asm/kvm_host.h | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/s390/include/asm/kvm_host.h
>> b/arch/s390/include/asm/kvm_host.h index 0ea82152d2f7..2d50f6c432e2
>> 100644 --- a/arch/s390/include/asm/kvm_host.h
>> +++ b/arch/s390/include/asm/kvm_host.h
>> @@ -344,7 +344,7 @@ struct kvm_s390_sie_block {
>> __u64 itdba; /* 0x01e8 */
>> __u64 riccbd; /* 0x01f0 */
>> __u64 gvrd; /* 0x01f8 */
>> -} __attribute__((packed));
>> +} __packed __aligned(512);
>>
>> struct kvm_s390_itdb {
>> __u8 data[256];
>
> I agree with the addition of aligned, but did you really have to remove
> packed? it makes me a little uncomfortable.
There is still "__packed".
--
Thanks,
David / dhildenb
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] KVM: s390: mark sie block as 512 byte aligned
2020-03-16 12:11 ` David Hildenbrand
@ 2020-03-16 14:22 ` Claudio Imbrenda
0 siblings, 0 replies; 6+ messages in thread
From: Claudio Imbrenda @ 2020-03-16 14:22 UTC (permalink / raw)
To: David Hildenbrand
Cc: Christian Borntraeger, Janosch Frank, KVM, Cornelia Huck,
linux-s390, Thomas Huth
On Mon, 16 Mar 2020 13:11:30 +0100
David Hildenbrand <david@redhat.com> wrote:
> On 16.03.20 13:10, Claudio Imbrenda wrote:
> > On Wed, 11 Mar 2020 09:33:04 +0100
> > Christian Borntraeger <borntraeger@de.ibm.com> wrote:
> >
> >> The sie block must be aligned to 512 bytes. Mark it as such.
> >>
> >> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> >> ---
> >> arch/s390/include/asm/kvm_host.h | 2 +-
> >> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/arch/s390/include/asm/kvm_host.h
> >> b/arch/s390/include/asm/kvm_host.h index 0ea82152d2f7..2d50f6c432e2
> >> 100644 --- a/arch/s390/include/asm/kvm_host.h
> >> +++ b/arch/s390/include/asm/kvm_host.h
> >> @@ -344,7 +344,7 @@ struct kvm_s390_sie_block {
> >> __u64 itdba; /* 0x01e8 */
> >> __u64 riccbd; /* 0x01f0 */
> >> __u64 gvrd; /* 0x01f8 */
> >> -} __attribute__((packed));
> >> +} __packed __aligned(512);
> >>
> >> struct kvm_s390_itdb {
> >> __u8 data[256];
> >
> > I agree with the addition of aligned, but did you really have to
> > remove packed? it makes me a little uncomfortable.
>
> There is still "__packed".
>
I had somehow totally missed it
this is what happens when you start working before actually waking up :D
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2020-03-16 14:22 UTC | newest]
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2020-03-11 8:33 [PATCH] KVM: s390: mark sie block as 512 byte aligned Christian Borntraeger
2020-03-11 8:41 ` David Hildenbrand
2020-03-11 10:37 ` Christian Borntraeger
2020-03-16 12:10 ` Claudio Imbrenda
2020-03-16 12:11 ` David Hildenbrand
2020-03-16 14:22 ` Claudio Imbrenda
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