98 lines
3.3 KiB
Diff
98 lines
3.3 KiB
Diff
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# HG changeset patch
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# User Jan Beulich <jbeulich@suse.com>
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# Date 1328801956 -3600
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# Node ID 9fc810bb814558bc5c8f9d086af7576516e07244
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# Parent fb71a97fe339282965d584663236ce71a2400659
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gnttab: miscellaneous fixes
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- _GTF_* constants name bit positions, so binary arithmetic on them is
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wrong
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- gnttab_clear_flag() cannot (on x86 and ia64 at least) simply use
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clear_bit(), as that may access more than the two bytes that are
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intended to be accessed
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Signed-off-by: Jan Beulich <jbeulich@suse.com>
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Acked-by: Keir Fraser <keir@xen.org>
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--- a/xen/common/grant_table.c
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+++ b/xen/common/grant_table.c
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@@ -389,7 +389,8 @@ static int _set_status_v2(domid_t domid
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(id != domid) ||
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(!readonly && (flags & GTF_readonly)) )
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{
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- gnttab_clear_flag(_GTF_reading | _GTF_writing, status);
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+ gnttab_clear_flag(_GTF_writing, status);
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+ gnttab_clear_flag(_GTF_reading, status);
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PIN_FAIL(done, GNTST_general_error,
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"Unstable flags (%x) or dom (%d). (expected dom %d) "
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"(r/w: %d)\n",
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@@ -1704,14 +1705,14 @@ __release_grant_for_copy(
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under the domain's grant table lock. */
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/* Only safe on transitive grants. Even then, note that we don't
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attempt to drop any pin on the referent grant. */
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-static void __fixup_status_for_pin(struct active_grant_entry *act,
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+static void __fixup_status_for_pin(const struct active_grant_entry *act,
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uint16_t *status)
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{
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if ( !(act->pin & GNTPIN_hstw_mask) )
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- *status &= ~_GTF_writing;
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+ *status &= ~GTF_writing;
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if ( !(act->pin & GNTPIN_hstr_mask) )
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- *status &= ~_GTF_reading;
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+ *status &= ~GTF_reading;
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}
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/* Grab a frame number from a grant entry and update the flags and pin
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--- a/xen/include/asm-ia64/grant_table.h
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+++ b/xen/include/asm-ia64/grant_table.h
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@@ -5,6 +5,8 @@
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#ifndef __ASM_GRANT_TABLE_H__
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#define __ASM_GRANT_TABLE_H__
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+#include <asm/intrinsics.h>
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+
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#define INITIAL_NR_GRANT_FRAMES 1
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// for grant map/unmap
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@@ -82,9 +84,19 @@ int guest_physmap_add_page(struct domain
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#define gnttab_mark_dirty(d, f) ((void)f)
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-static inline void gnttab_clear_flag(unsigned long nr, uint16_t *addr)
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+static inline void gnttab_clear_flag(unsigned int nr, volatile uint16_t *st)
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{
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- clear_bit(nr, addr);
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+ /*
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+ * Note that this cannot be clear_bit(), as the access must be
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+ * confined to the specified 2 bytes.
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+ */
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+ uint16_t mask = ~(1 << nr), old;
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+ CMPXCHG_BUGCHECK_DECL
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+
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+ do {
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+ CMPXCHG_BUGCHECK(st);
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+ old = *st;
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+ } while (cmpxchg_rel(st, old, old & mask) != old);
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}
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#define gnttab_host_mapping_get_page_type(op, ld, rd) \
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--- a/xen/include/asm-x86/grant_table.h
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+++ b/xen/include/asm-x86/grant_table.h
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@@ -48,9 +48,13 @@ int replace_grant_host_mapping(
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#define gnttab_mark_dirty(d, f) paging_mark_dirty((d), (f))
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-static inline void gnttab_clear_flag(unsigned long nr, uint16_t *addr)
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+static inline void gnttab_clear_flag(unsigned int nr, uint16_t *st)
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{
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- clear_bit(nr, (unsigned long *)addr);
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+ /*
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+ * Note that this cannot be clear_bit(), as the access must be
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+ * confined to the specified 2 bytes.
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+ */
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+ asm volatile ("lock btrw %1,%0" : "=m" (*st) : "Ir" (nr), "m" (*st));
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}
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/* Foreign mappings of HHVM-guest pages do not modify the type count. */
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