pvcalls: Document correctly and explicitely the padding for all arches

The specification 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 have a different size between
32-bit x86 and 64-bit x86.

For all the other architectures supported (Arm and 64-bit x86), the
structure have the sames sizes because they contain implicit padding
thanks to the 64-bit alignment of the field uint64_t field.

Given the specification is authoritative, the padding will now be the
same for all architectures. The potential breakage of compatibility is
ought to be fine as pvcalls is still a tech preview.

Signed-off-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Release-acked-by: Paul Durrant <paul@xen.org>
Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>

diff --git a/docs/misc/pvcalls.pandoc b/docs/misc/pvcalls.pandoc
index 665dad556c398be39c409b9577f6525a1930f696..971cd8f4b1225d70b5cca31a3fe5121ddb8ae459 100644 (file)
--- a/docs/misc/pvcalls.pandoc
+++ b/docs/misc/pvcalls.pandoc
@@ -246,9 +246,7 @@ The format is defined as follows:
                        uint32_t domain;
                        uint32_t type;
                        uint32_t protocol;
-                       #ifdef CONFIG_X86_32
                        uint8_t pad[4];
-                       #endif
                } socket;
                struct xen_pvcalls_connect {
                        uint64_t id;
@@ -257,16 +255,12 @@ The format is defined as follows:
                        uint32_t flags;
                        grant_ref_t ref;
                        uint32_t evtchn;
-                       #ifdef CONFIG_X86_32
                        uint8_t pad[4];
-                       #endif
                } connect;
                struct xen_pvcalls_release {
                        uint64_t id;
                        uint8_t reuse;
-                       #ifdef CONFIG_X86_32
                        uint8_t pad[7];
-                       #endif
                } release;
                struct xen_pvcalls_bind {
                        uint64_t id;
@@ -276,9 +270,7 @@ The format is defined as follows:
                struct xen_pvcalls_listen {
                        uint64_t id;
                        uint32_t backlog;
-                       #ifdef CONFIG_X86_32
                        uint8_t pad[4];
-                       #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 905880735dda3e02bae5c2bf2c3df87b99e957a5..6da6b5533a10960da0082c3e91432a8cee04a8bb 100644 (file)
--- a/xen/include/public/io/pvcalls.h
+++ b/xen/include/public/io/pvcalls.h
@@ -68,6 +68,7 @@ struct xen_pvcalls_request {
             uint32_t domain;
             uint32_t type;
             uint32_t protocol;
+            uint8_t pad[4];
         } socket;
         struct xen_pvcalls_connect {
             uint64_t id;
@@ -76,10 +77,12 @@ struct xen_pvcalls_request {
             uint32_t flags;
             grant_ref_t ref;
             uint32_t evtchn;
+            uint8_t pad[4];
         } connect;
         struct xen_pvcalls_release {
             uint64_t id;
             uint8_t reuse;
+            uint8_t pad[7];
         } release;
         struct xen_pvcalls_bind {
             uint64_t id;
@@ -89,6 +92,7 @@ struct xen_pvcalls_request {
         struct xen_pvcalls_listen {
             uint64_t id;
             uint32_t backlog;
+            uint8_t pad[4];
         } listen;
         struct xen_pvcalls_accept {
             uint64_t id;