[PATCH] shared_info size and padding fixes

[John Levon <levon@movementarian.org>]

# HG changeset patch
# User john.levon@sun.com
# Date 1155157246 -3600
# Node ID e24df0e22cdfe6daaa0d4d40c88e13c0427a1515
# Parent  b60ea69932b1a4d10c3aae945a1ce1aa160c689b
sizeof(shared_info_t) can change even in compatible hypervisor versions.
Add a clear warning about this, and fix the few places relying on it.
In addition, add some padding to arch_shared_info, to allow future
additions to the structure without breaking known offsets of members
following it in the shared info.

Signed-off-by: John Levon <john.levon@sun.com>

diff -r b60ea69932b1 -r e24df0e22cdf tools/libxc/xc_hvm_build.c
--- a/tools/libxc/xc_hvm_build.c	Wed Aug 09 18:04:20 2006 +0100
+++ b/tools/libxc/xc_hvm_build.c	Wed Aug 09 22:00:46 2006 +0100
@@ -304,7 +304,7 @@ static int setup_guest(int xc_handle,
               xc_handle, dom, PAGE_SIZE, PROT_READ | PROT_WRITE,
               shared_info_frame)) == 0 )
         goto error_out;
-    memset(shared_info, 0, sizeof(shared_info_t));
+    memset(shared_info, 0, PAGE_SIZE);
     /* Mask all upcalls... */
     for ( i = 0; i < MAX_VIRT_CPUS; i++ )
         shared_info->vcpu_info[i].evtchn_upcall_mask = 1;
diff -r b60ea69932b1 -r e24df0e22cdf tools/libxc/xc_linux_build.c
--- a/tools/libxc/xc_linux_build.c	Wed Aug 09 18:04:20 2006 +0100
+++ b/tools/libxc/xc_linux_build.c	Wed Aug 09 22:00:46 2006 +0100
@@ -593,7 +593,7 @@ static int setup_guest(int xc_handle,
         xc_handle, dom, PAGE_SIZE, PROT_READ|PROT_WRITE, shared_info_frame);
     printf("shared_info = %p, err=%s frame=%lx\n",
            shared_info, strerror (errno), shared_info_frame);
-    //memset(shared_info, 0, sizeof(shared_info_t));
+    //memset(shared_info, 0, PAGE_SIZE);
     /* Mask all upcalls... */
     for ( i = 0; i < MAX_VIRT_CPUS; i++ )
         shared_info->vcpu_info[i].evtchn_upcall_mask = 1;
@@ -1064,7 +1064,7 @@ static int setup_guest(int xc_handle,
     /* shared_info page starts its life empty. */
     shared_info = xc_map_foreign_range(
         xc_handle, dom, PAGE_SIZE, PROT_READ|PROT_WRITE, shared_info_frame);
-    memset(shared_info, 0, sizeof(shared_info_t));
+    memset(shared_info, 0, PAGE_SIZE);
     /* Mask all upcalls... */
     for ( i = 0; i < MAX_VIRT_CPUS; i++ )
         shared_info->vcpu_info[i].evtchn_upcall_mask = 1;
diff -r b60ea69932b1 -r e24df0e22cdf tools/libxc/xc_linux_restore.c
--- a/tools/libxc/xc_linux_restore.c	Wed Aug 09 18:04:20 2006 +0100
+++ b/tools/libxc/xc_linux_restore.c	Wed Aug 09 22:00:46 2006 +0100
@@ -737,7 +737,7 @@ int xc_linux_restore(int xc_handle, int 
     /* Copy saved contents of shared-info page. No checking needed. */
     page = xc_map_foreign_range(
         xc_handle, dom, PAGE_SIZE, PROT_WRITE, shared_info_frame);
-    memcpy(page, shared_info, sizeof(shared_info_t));
+    memcpy(page, shared_info, PAGE_SIZE);
     munmap(page, PAGE_SIZE);
 
     /* Uncanonicalise the pfn-to-mfn table frame-number list. */
diff -r b60ea69932b1 -r e24df0e22cdf xen/arch/ia64/asm-offsets.c
--- a/xen/arch/ia64/asm-offsets.c	Wed Aug 09 18:04:20 2006 +0100
+++ b/xen/arch/ia64/asm-offsets.c	Wed Aug 09 22:00:46 2006 +0100
@@ -31,7 +31,6 @@ void foo(void)
 	DEFINE(IA64_SWITCH_STACK_SIZE, sizeof (struct switch_stack));
 	DEFINE(IA64_CPU_SIZE, sizeof (struct cpuinfo_ia64));
 	DEFINE(UNW_FRAME_INFO_SIZE, sizeof (struct unw_frame_info));
-	DEFINE(SHARED_INFO_SIZE, sizeof (struct shared_info));
 
 	BLANK();
 	DEFINE(IA64_MCA_CPU_INIT_STACK_OFFSET, offsetof (struct ia64_mca_cpu, init_stack));
diff -r b60ea69932b1 -r e24df0e22cdf xen/include/public/arch-ia64.h
--- a/xen/include/public/arch-ia64.h	Wed Aug 09 18:04:20 2006 +0100
+++ b/xen/include/public/arch-ia64.h	Wed Aug 09 22:00:46 2006 +0100
@@ -297,6 +297,8 @@ struct arch_shared_info {
 
     /* Interrupt vector for event channel.  */
     int evtchn_vector;
+
+    uint64_t pad[32];
 };
 typedef struct arch_shared_info arch_shared_info_t;
 
diff -r b60ea69932b1 -r e24df0e22cdf xen/include/public/arch-powerpc.h
--- a/xen/include/public/arch-powerpc.h	Wed Aug 09 18:04:20 2006 +0100
+++ b/xen/include/public/arch-powerpc.h	Wed Aug 09 22:00:46 2006 +0100
@@ -107,6 +107,7 @@ DEFINE_XEN_GUEST_HANDLE(vcpu_guest_conte
 DEFINE_XEN_GUEST_HANDLE(vcpu_guest_context_t);
 
 struct arch_shared_info {
+    uint64_t pad[32];
 };
 
 struct arch_vcpu_info {
diff -r b60ea69932b1 -r e24df0e22cdf xen/include/public/arch-x86_32.h
--- a/xen/include/public/arch-x86_32.h	Wed Aug 09 18:04:20 2006 +0100
+++ b/xen/include/public/arch-x86_32.h	Wed Aug 09 22:00:46 2006 +0100
@@ -191,6 +191,7 @@ struct arch_shared_info {
     /* Frame containing list of mfns containing list of mfns containing p2m. */
     xen_pfn_t     pfn_to_mfn_frame_list_list;
     unsigned long nmi_reason;
+    uint64_t pad[32];
 };
 typedef struct arch_shared_info arch_shared_info_t;
 
diff -r b60ea69932b1 -r e24df0e22cdf xen/include/public/arch-x86_64.h
--- a/xen/include/public/arch-x86_64.h	Wed Aug 09 18:04:20 2006 +0100
+++ b/xen/include/public/arch-x86_64.h	Wed Aug 09 22:00:46 2006 +0100
@@ -261,6 +261,7 @@ struct arch_shared_info {
     /* Frame containing list of mfns containing list of mfns containing p2m. */
     xen_pfn_t     pfn_to_mfn_frame_list_list;
     unsigned long nmi_reason;
+    uint64_t pad[32];
 };
 typedef struct arch_shared_info arch_shared_info_t;
 
diff -r b60ea69932b1 -r e24df0e22cdf xen/include/public/xen.h
--- a/xen/include/public/xen.h	Wed Aug 09 18:04:20 2006 +0100
+++ b/xen/include/public/xen.h	Wed Aug 09 22:00:46 2006 +0100
@@ -376,7 +376,11 @@ typedef struct vcpu_info vcpu_info_t;
 
 /*
  * Xen/kernel shared data -- pointer provided in start_info.
- * NB. We expect that this struct is smaller than a page.
+ *
+ * This structure is defined to be both smaller than a page, and the
+ * only data on the page, but may vary in actual size even within
+ * compatible Xen versions; domains should never rely on the actual
+ * size of this structure.
  */
 struct shared_info {
     struct vcpu_info vcpu_info[MAX_VIRT_CPUS];