| Message ID | 20200516101953.1235-1-julien@xen.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | pvcalls: Document correctly and explicitely the padding for all arches | expand |
Sorry I forgot to CC the maintainers on the e-mail. I will resent it. On 16/05/2020 11:19, Julien Grall wrote: > From: Julien Grall <jgrall@amazon.com> > > The documentation of pvcalls suggests there is padding for 32-bit x86 > at the end of most the structure. However, they are not described in > in the public header. > > Because of that all the structures would be 32-bit aligned and not > 64-bit aligned for 32-bit x86. > > For all the other architectures supported (Arm and 64-bit x86), the > structure are aligned to 64-bit because they contain uint64_t field. > Therefore all the structures contain implicit padding. > > The paddings are now corrected for 32-bit x86 and written explicitly for > all the architectures. > > While the structure size between 32-bit and 64-bit x86 is different, it > shouldn't cause any incompatibility between a 32-bit and 64-bit > frontend/backend because the commands are always 56 bits and the padding > are at the end of the structure. > > As an aside, the padding sadly cannot be mandated to be 0 as they are > already present. So it is not going to be possible to use the padding > for extending a command in the future. > > Signed-off-by: Julien Grall <jgrall@amazon.com> > > --- > Changes in v2: > - It is not possible to use the same padding for 32-bit x86 and > all the other supported architectures. > --- > docs/misc/pvcalls.pandoc | 18 ++++++++++-------- > xen/include/public/io/pvcalls.h | 14 ++++++++++++++ > 2 files changed, 24 insertions(+), 8 deletions(-) > > diff --git a/docs/misc/pvcalls.pandoc b/docs/misc/pvcalls.pandoc > index 665dad556c39..c25412868f5d 100644 > --- a/docs/misc/pvcalls.pandoc > +++ b/docs/misc/pvcalls.pandoc > @@ -246,9 +246,9 @@ The format is defined as follows: > uint32_t domain; > uint32_t type; > uint32_t protocol; > - #ifdef CONFIG_X86_32 > + #ifndef CONFIG_X86_32 > uint8_t pad[4]; > - #endif > + #endif > } socket; > struct xen_pvcalls_connect { > uint64_t id; > @@ -257,16 +257,18 @@ The format is defined as follows: > uint32_t flags; > grant_ref_t ref; > uint32_t evtchn; > - #ifdef CONFIG_X86_32 > + #ifndef CONFIG_X86_32 > uint8_t pad[4]; > - #endif > + #endif > } connect; > struct xen_pvcalls_release { > uint64_t id; > uint8_t reuse; > - #ifdef CONFIG_X86_32 > + #ifndef CONFIG_X86_32 > uint8_t pad[7]; > - #endif > + #else > + uint8_t pad[3]; > + #endif > } release; > struct xen_pvcalls_bind { > uint64_t id; > @@ -276,9 +278,9 @@ The format is defined as follows: > struct xen_pvcalls_listen { > uint64_t id; > uint32_t backlog; > - #ifdef CONFIG_X86_32 > + #ifndef CONFIG_X86_32 > uint8_t pad[4]; > - #endif > + #endif > } listen; > struct xen_pvcalls_accept { > uint64_t id; > diff --git a/xen/include/public/io/pvcalls.h b/xen/include/public/io/pvcalls.h > index cb8171275c13..590c5e9e41aa 100644 > --- a/xen/include/public/io/pvcalls.h > +++ b/xen/include/public/io/pvcalls.h > @@ -65,6 +65,9 @@ struct xen_pvcalls_request { > uint32_t domain; > uint32_t type; > uint32_t protocol; > +#ifndef CONFIG_X86_32 > + uint8_t pad[4]; > +#endif > } socket; > struct xen_pvcalls_connect { > uint64_t id; > @@ -73,10 +76,18 @@ struct xen_pvcalls_request { > uint32_t flags; > grant_ref_t ref; > uint32_t evtchn; > +#ifndef CONFIG_X86_32 > + uint8_t pad[4]; > +#endif > } connect; > struct xen_pvcalls_release { > uint64_t id; > uint8_t reuse; > +#ifndef CONFIG_X86_32 > + uint8_t pad[7]; > +#else > + uint8_t pad[3]; > +#endif > } release; > struct xen_pvcalls_bind { > uint64_t id; > @@ -86,6 +97,9 @@ struct xen_pvcalls_request { > struct xen_pvcalls_listen { > uint64_t id; > uint32_t backlog; > +#ifndef CONFIG_X86_32 > + uint8_t pad[4]; > +#endif > } listen; > struct xen_pvcalls_accept { > uint64_t id; >
diff --git a/docs/misc/pvcalls.pandoc b/docs/misc/pvcalls.pandoc index 665dad556c39..c25412868f5d 100644 --- a/docs/misc/pvcalls.pandoc +++ b/docs/misc/pvcalls.pandoc @@ -246,9 +246,9 @@ The format is defined as follows: uint32_t domain; uint32_t type; uint32_t protocol; - #ifdef CONFIG_X86_32 + #ifndef CONFIG_X86_32 uint8_t pad[4]; - #endif + #endif } socket; struct xen_pvcalls_connect { uint64_t id; @@ -257,16 +257,18 @@ The format is defined as follows: uint32_t flags; grant_ref_t ref; uint32_t evtchn; - #ifdef CONFIG_X86_32 + #ifndef CONFIG_X86_32 uint8_t pad[4]; - #endif + #endif } connect; struct xen_pvcalls_release { uint64_t id; uint8_t reuse; - #ifdef CONFIG_X86_32 + #ifndef CONFIG_X86_32 uint8_t pad[7]; - #endif + #else + uint8_t pad[3]; + #endif } release; struct xen_pvcalls_bind { uint64_t id; @@ -276,9 +278,9 @@ The format is defined as follows: struct xen_pvcalls_listen { uint64_t id; uint32_t backlog; - #ifdef CONFIG_X86_32 + #ifndef CONFIG_X86_32 uint8_t pad[4]; - #endif + #endif } listen; struct xen_pvcalls_accept { uint64_t id; diff --git a/xen/include/public/io/pvcalls.h b/xen/include/public/io/pvcalls.h index cb8171275c13..590c5e9e41aa 100644 --- a/xen/include/public/io/pvcalls.h +++ b/xen/include/public/io/pvcalls.h @@ -65,6 +65,9 @@ struct xen_pvcalls_request { uint32_t domain; uint32_t type; uint32_t protocol; +#ifndef CONFIG_X86_32 + uint8_t pad[4]; +#endif } socket; struct xen_pvcalls_connect { uint64_t id; @@ -73,10 +76,18 @@ struct xen_pvcalls_request { uint32_t flags; grant_ref_t ref; uint32_t evtchn; +#ifndef CONFIG_X86_32 + uint8_t pad[4]; +#endif } connect; struct xen_pvcalls_release { uint64_t id; uint8_t reuse; +#ifndef CONFIG_X86_32 + uint8_t pad[7]; +#else + uint8_t pad[3]; +#endif } release; struct xen_pvcalls_bind { uint64_t id; @@ -86,6 +97,9 @@ struct xen_pvcalls_request { struct xen_pvcalls_listen { uint64_t id; uint32_t backlog; +#ifndef CONFIG_X86_32 + uint8_t pad[4]; +#endif } listen; struct xen_pvcalls_accept { uint64_t id;