# HG changeset patch
# User Tim Deegan <Tim.Deegan@xxxxxxxxxxxxx>
# Date 1166615581 0
# Node ID d9685264b28cdaa39d2eef62a8c6c9df731be0bd
# Parent bcaf2f568ebdd00812dd4c9e50f890b958d86ff7
[XEN] Better diagnostics of recursive shadow faults
Give a trace of the recursive fault instead of BUG()ing in the shadow handler.
Signed-off-by: Tim Deegan <Tim.Deegan@xxxxxxxxxxxxx>
Based on xen-unstable changeset 13101:f7a2cd8b0a8e03e94babc88c9c25fb5008f7a125
---
xen/arch/x86/mm/shadow/common.c | 44 ++++++++++++++++++++--------------------
xen/arch/x86/mm/shadow/multi.c | 24 ++++++++++++++++-----
xen/include/asm-x86/shadow.h | 6 ++---
3 files changed, 43 insertions(+), 31 deletions(-)
diff -r bcaf2f568ebd -r d9685264b28c xen/arch/x86/mm/shadow/common.c
--- a/xen/arch/x86/mm/shadow/common.c Wed Dec 20 11:39:22 2006 +0000
+++ b/xen/arch/x86/mm/shadow/common.c Wed Dec 20 11:53:01 2006 +0000
@@ -553,7 +553,7 @@ shadow_validate_guest_entry(struct vcpu
{
int rc;
- ASSERT(shadow_lock_is_acquired(v->domain));
+ ASSERT(shadow_locked_by_me(v->domain));
rc = __shadow_validate_guest_entry(v, gmfn, entry, sizeof(l1_pgentry_t));
shadow_audit_tables(v);
return rc;
@@ -569,7 +569,7 @@ shadow_validate_guest_pt_write(struct vc
struct domain *d = v->domain;
int rc;
- ASSERT(shadow_lock_is_acquired(v->domain));
+ ASSERT(shadow_locked_by_me(v->domain));
rc = __shadow_validate_guest_entry(v, gmfn, entry, size);
if ( rc & SHADOW_SET_FLUSH )
/* Need to flush TLBs to pick up shadow PT changes */
@@ -858,7 +858,7 @@ mfn_t shadow_alloc(struct domain *d,
void *p;
int i;
- ASSERT(shadow_lock_is_acquired(d));
+ ASSERT(shadow_locked_by_me(d));
ASSERT(order <= SHADOW_MAX_ORDER);
ASSERT(shadow_type != SH_type_none);
perfc_incrc(shadow_alloc);
@@ -928,7 +928,7 @@ void shadow_free(struct domain *d, mfn_t
unsigned long mask;
int i;
- ASSERT(shadow_lock_is_acquired(d));
+ ASSERT(shadow_locked_by_me(d));
perfc_incrc(shadow_free);
shadow_type = sp->type;
@@ -997,7 +997,7 @@ shadow_alloc_p2m_pages(struct domain *d)
{
struct page_info *pg;
u32 i;
- ASSERT(shadow_lock_is_acquired(d));
+ ASSERT(shadow_locked_by_me(d));
if ( d->arch.shadow.total_pages
< (shadow_min_acceptable_pages(d) + (1<<SHADOW_MAX_ORDER)) )
@@ -1143,7 +1143,7 @@ p2m_next_level(struct domain *d, mfn_t *
p2m_install_entry_in_monitors(d, (l3_pgentry_t *)p2m_entry);
/* Also, any vcpus running on shadows of the p2m need to
* reload their CR3s so the change propagates to the shadow */
- ASSERT(shadow_lock_is_acquired(d));
+ ASSERT(shadow_locked_by_me(d));
for_each_vcpu(d, v)
{
if ( pagetable_get_pfn(v->arch.guest_table)
@@ -1435,7 +1435,7 @@ static unsigned int set_sh_allocation(st
unsigned int lower_bound;
int j;
- ASSERT(shadow_lock_is_acquired(d));
+ ASSERT(shadow_locked_by_me(d));
/* Don't allocate less than the minimum acceptable, plus one page per
* megabyte of RAM (for the p2m table) */
@@ -1614,7 +1614,7 @@ static int shadow_hash_alloc(struct doma
{
struct shadow_page_info **table;
- ASSERT(shadow_lock_is_acquired(d));
+ ASSERT(shadow_locked_by_me(d));
ASSERT(!d->arch.shadow.hash_table);
table = xmalloc_array(struct shadow_page_info *, SHADOW_HASH_BUCKETS);
@@ -1629,7 +1629,7 @@ static int shadow_hash_alloc(struct doma
* This function does not care whether the table is populated. */
static void shadow_hash_teardown(struct domain *d)
{
- ASSERT(shadow_lock_is_acquired(d));
+ ASSERT(shadow_locked_by_me(d));
ASSERT(d->arch.shadow.hash_table);
xfree(d->arch.shadow.hash_table);
@@ -1645,7 +1645,7 @@ mfn_t shadow_hash_lookup(struct vcpu *v,
struct shadow_page_info *sp, *prev;
key_t key;
- ASSERT(shadow_lock_is_acquired(d));
+ ASSERT(shadow_locked_by_me(d));
ASSERT(d->arch.shadow.hash_table);
ASSERT(t);
@@ -1699,7 +1699,7 @@ void shadow_hash_insert(struct vcpu *v,
struct shadow_page_info *sp;
key_t key;
- ASSERT(shadow_lock_is_acquired(d));
+ ASSERT(shadow_locked_by_me(d));
ASSERT(d->arch.shadow.hash_table);
ASSERT(t);
@@ -1725,7 +1725,7 @@ void shadow_hash_delete(struct vcpu *v,
struct shadow_page_info *sp, *x;
key_t key;
- ASSERT(shadow_lock_is_acquired(d));
+ ASSERT(shadow_locked_by_me(d));
ASSERT(d->arch.shadow.hash_table);
ASSERT(t);
@@ -1780,7 +1780,7 @@ static void hash_foreach(struct vcpu *v,
struct shadow_page_info *x;
/* Say we're here, to stop hash-lookups reordering the chains */
- ASSERT(shadow_lock_is_acquired(d));
+ ASSERT(shadow_locked_by_me(d));
ASSERT(d->arch.shadow.hash_walking == 0);
d->arch.shadow.hash_walking = 1;
@@ -1937,7 +1937,7 @@ int shadow_remove_write_access(struct vc
;
struct page_info *pg = mfn_to_page(gmfn);
- ASSERT(shadow_lock_is_acquired(v->domain));
+ ASSERT(shadow_locked_by_me(v->domain));
/* Only remove writable mappings if we are doing shadow refcounts.
* In guest refcounting, we trust Xen to already be restricting
@@ -2129,7 +2129,7 @@ int shadow_remove_all_mappings(struct vc
if ( (page->count_info & PGC_count_mask) == 0 )
return 0;
- ASSERT(shadow_lock_is_acquired(v->domain));
+ ASSERT(shadow_locked_by_me(v->domain));
/* XXX TODO:
* Heuristics for finding the (probably) single mapping of this gmfn */
@@ -2296,7 +2296,7 @@ void sh_remove_shadows(struct vcpu *v, m
0 /* unused */
};
- ASSERT(shadow_lock_is_acquired(v->domain));
+ ASSERT(shadow_locked_by_me(v->domain));
ASSERT(!(all && fast));
pg = mfn_to_page(gmfn);
@@ -2382,7 +2382,7 @@ void sh_update_paging_modes(struct vcpu
struct shadow_paging_mode *old_mode = v->arch.shadow.mode;
mfn_t old_guest_table;
- ASSERT(shadow_lock_is_acquired(d));
+ ASSERT(shadow_locked_by_me(d));
// Valid transitions handled by this function:
// - For PV guests:
@@ -2560,7 +2560,7 @@ static void sh_new_mode(struct domain *d
{
struct vcpu *v;
- ASSERT(shadow_lock_is_acquired(d));
+ ASSERT(shadow_locked_by_me(d));
ASSERT(d != current->domain);
d->arch.shadow.mode = new_mode;
if ( new_mode & SHM2_translate )
@@ -2661,7 +2661,7 @@ void shadow_teardown(struct domain *d)
ASSERT(test_bit(_DOMF_dying, &d->domain_flags));
ASSERT(d != current->domain);
- if ( !shadow_lock_is_acquired(d) )
+ if ( !shadow_locked_by_me(d) )
shadow_lock(d); /* Keep various asserts happy */
if ( shadow_mode_enabled(d) )
@@ -2744,7 +2744,7 @@ static int shadow_one_bit_enable(struct
static int shadow_one_bit_enable(struct domain *d, u32 mode)
/* Turn on a single shadow mode feature */
{
- ASSERT(shadow_lock_is_acquired(d));
+ ASSERT(shadow_locked_by_me(d));
/* Sanity check the call */
if ( d == current->domain || (d->arch.shadow.mode & mode) )
@@ -2773,7 +2773,7 @@ static int shadow_one_bit_disable(struct
/* Turn off a single shadow mode feature */
{
struct vcpu *v;
- ASSERT(shadow_lock_is_acquired(d));
+ ASSERT(shadow_locked_by_me(d));
/* Sanity check the call */
if ( d == current->domain || !(d->arch.shadow.mode & mode) )
@@ -3134,7 +3134,7 @@ void sh_do_mark_dirty(struct domain *d,
{
unsigned long pfn;
- ASSERT(shadow_lock_is_acquired(d));
+ ASSERT(shadow_locked_by_me(d));
ASSERT(shadow_mode_log_dirty(d));
if ( !mfn_valid(gmfn) )
diff -r bcaf2f568ebd -r d9685264b28c xen/arch/x86/mm/shadow/multi.c
--- a/xen/arch/x86/mm/shadow/multi.c Wed Dec 20 11:39:22 2006 +0000
+++ b/xen/arch/x86/mm/shadow/multi.c Wed Dec 20 11:53:01 2006 +0000
@@ -227,7 +227,7 @@ static inline int
static inline int
guest_walk_tables(struct vcpu *v, unsigned long va, walk_t *gw, int guest_op)
{
- ASSERT(!guest_op || shadow_lock_is_acquired(v->domain));
+ ASSERT(!guest_op || shadow_locked_by_me(v->domain));
perfc_incrc(shadow_guest_walk);
memset(gw, 0, sizeof(*gw));
@@ -442,7 +442,7 @@ static u32 guest_set_ad_bits(struct vcpu
ASSERT(ep && !(((unsigned long)ep) & ((sizeof *ep) - 1)));
ASSERT(level <= GUEST_PAGING_LEVELS);
- ASSERT(shadow_lock_is_acquired(v->domain));
+ ASSERT(shadow_locked_by_me(v->domain));
flags = guest_l1e_get_flags(*ep);
@@ -2657,6 +2657,18 @@ static int sh_page_fault(struct vcpu *v,
}
#endif /* SHOPT_FAST_FAULT_PATH */
+ /* Detect if this page fault happened while we were already in Xen
+ * doing a shadow operation. If that happens, the only thing we can
+ * do is let Xen's normal fault handlers try to fix it. In any case,
+ * a diagnostic trace of the fault will be more useful than
+ * a BUG() when we try to take the lock again. */
+ if ( unlikely(shadow_locked_by_me(d)) )
+ {
+ SHADOW_ERROR("Recursive shadow fault: lock was taken by %s\n",
+ d->arch.shadow.locker_function);
+ return 0;
+ }
+
shadow_lock(d);
shadow_audit_tables(v);
@@ -3343,7 +3355,7 @@ sh_update_cr3(struct vcpu *v)
u32 guest_idx=0;
#endif
- ASSERT(shadow_lock_is_acquired(v->domain));
+ ASSERT(shadow_locked_by_me(v->domain));
ASSERT(v->arch.shadow.mode);
////
@@ -3837,7 +3849,7 @@ sh_x86_emulate_write(struct vcpu *v, uns
if ( vaddr & (bytes-1) )
return X86EMUL_UNHANDLEABLE;
- ASSERT(shadow_lock_is_acquired(v->domain));
+ ASSERT(shadow_locked_by_me(v->domain));
ASSERT(((vaddr & ~PAGE_MASK) + bytes) <= PAGE_SIZE);
if ( (addr = emulate_map_dest(v, vaddr, sh_ctxt, &mfn)) == NULL )
@@ -3865,7 +3877,7 @@ sh_x86_emulate_cmpxchg(struct vcpu *v, u
unsigned long prev;
int rv = X86EMUL_CONTINUE;
- ASSERT(shadow_lock_is_acquired(v->domain));
+ ASSERT(shadow_locked_by_me(v->domain));
ASSERT(bytes <= sizeof(unsigned long));
if ( vaddr & (bytes-1) )
@@ -3914,7 +3926,7 @@ sh_x86_emulate_cmpxchg8b(struct vcpu *v,
u64 old, new, prev;
int rv = X86EMUL_CONTINUE;
- ASSERT(shadow_lock_is_acquired(v->domain));
+ ASSERT(shadow_locked_by_me(v->domain));
if ( vaddr & 7 )
return X86EMUL_UNHANDLEABLE;
diff -r bcaf2f568ebd -r d9685264b28c xen/include/asm-x86/shadow.h
--- a/xen/include/asm-x86/shadow.h Wed Dec 20 11:39:22 2006 +0000
+++ b/xen/include/asm-x86/shadow.h Wed Dec 20 11:53:01 2006 +0000
@@ -105,7 +105,7 @@
(_d)->arch.shadow.locker_function = "nobody"; \
} while (0)
-#define shadow_lock_is_acquired(_d) \
+#define shadow_locked_by_me(_d) \
(current->processor == (_d)->arch.shadow.locker)
#define shadow_lock(_d) \
@@ -337,7 +337,7 @@ static inline void mark_dirty(struct dom
/* Internal version, for when the shadow lock is already held */
static inline void sh_mark_dirty(struct domain *d, mfn_t gmfn)
{
- ASSERT(shadow_lock_is_acquired(d));
+ ASSERT(shadow_locked_by_me(d));
if ( unlikely(shadow_mode_log_dirty(d)) )
sh_do_mark_dirty(d, gmfn);
}
@@ -552,7 +552,7 @@ extern void sh_remove_shadows(struct vcp
extern void sh_remove_shadows(struct vcpu *v, mfn_t gmfn, int fast, int all);
static inline void shadow_remove_all_shadows(struct vcpu *v, mfn_t gmfn)
{
- int was_locked = shadow_lock_is_acquired(v->domain);
+ int was_locked = shadow_locked_by_me(v->domain);
if ( !was_locked )
shadow_lock(v->domain);
sh_remove_shadows(v, gmfn, 0, 1);
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