[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] shared_info size and padding fixes
On Thu, Aug 10, 2006 at 02:29:25PM +0100, Keir Fraser wrote: > Your patch looked fine, by the way, except that adding padding to every > arch-specific portion of shared info seems unnecessary. On the presumption that silence means no, here's a patch without the padding. I sincerely hope whoever next changes these structures remembers the padding! regards john # HG changeset patch # User levon@xxxxxxxxxxxxxxxxx # Date 1155298435 -3600 # Node ID 43cc94ddfa1c31b1c0d288344ec3147fd61180e5 # Parent b60ea69932b1a4d10c3aae945a1ce1aa160c689b Add a clear warning that shared_info_t can change in size even in compatible ABI revisions. Fix a few places relying on its size. Signed-off-by: John Levon <john.levon@xxxxxxx> diff -r b60ea69932b1 -r 43cc94ddfa1c 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 Fri Aug 11 13:13:55 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 43cc94ddfa1c 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 Fri Aug 11 13:13:55 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 43cc94ddfa1c 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 Fri Aug 11 13:13:55 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 43cc94ddfa1c 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 Fri Aug 11 13:13:55 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]; _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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