# HG changeset patch
# User Tim Deegan <Tim.Deegan@xxxxxxxxxx>
# Date 1309426014 -3600
# Node ID 80e00ac43548717deedca484d483ebc41b78d076
# Parent 2115801e8e4786a666d768d7847721b7d5650275
Nested p2m: rework locking around nested-p2m flushes and updates.
The nestedp2m_lock now only covers the mapping from nested-cr3 to
nested-p2m; the tables themselves may be updated or flushed using only
the relevant p2m lock.
This means that the nested-p2m lock is only taken on one path, and
always before any p2m locks.
Signed-off-by: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Acked-by: Christoph Egger <Christoph.Egger@xxxxxxx>
---
diff -r 2115801e8e47 -r 80e00ac43548 xen/arch/x86/mm/hap/nested_hap.c
--- a/xen/arch/x86/mm/hap/nested_hap.c Thu Jun 30 10:26:54 2011 +0100
+++ b/xen/arch/x86/mm/hap/nested_hap.c Thu Jun 30 10:26:54 2011 +0100
@@ -96,17 +96,23 @@
/* NESTED VIRT FUNCTIONS */
/********************************************/
static void
-nestedhap_fix_p2m(struct p2m_domain *p2m, paddr_t L2_gpa, paddr_t L0_gpa,
- p2m_type_t p2mt, p2m_access_t p2ma)
+nestedhap_fix_p2m(struct vcpu *v, struct p2m_domain *p2m,
+ paddr_t L2_gpa, paddr_t L0_gpa,
+ p2m_type_t p2mt, p2m_access_t p2ma)
{
- int rv;
+ int rv = 1;
ASSERT(p2m);
ASSERT(p2m->set_entry);
p2m_lock(p2m);
- rv = set_p2m_entry(p2m, L2_gpa >> PAGE_SHIFT,
- page_to_mfn(maddr_to_page(L0_gpa)),
- 0 /*4K*/, p2mt, p2ma);
+
+ /* If this p2m table has been flushed or recycled under our feet,
+ * leave it alone. We'll pick up the right one as we try to
+ * vmenter the guest. */
+ if ( p2m->cr3 == nhvm_vcpu_hostcr3(v) )
+ rv = set_p2m_entry(p2m, L2_gpa >> PAGE_SHIFT,
+ page_to_mfn(maddr_to_page(L0_gpa)),
+ 0 /*4K*/, p2mt, p2ma);
p2m_unlock(p2m);
if (rv == 0) {
@@ -211,12 +217,10 @@
break;
}
- nestedp2m_lock(d);
/* fix p2m_get_pagetable(nested_p2m) */
- nestedhap_fix_p2m(nested_p2m, L2_gpa, L0_gpa,
+ nestedhap_fix_p2m(v, nested_p2m, L2_gpa, L0_gpa,
p2m_ram_rw,
p2m_access_rwx /* FIXME: Should use same permission as l1 guest */);
- nestedp2m_unlock(d);
return NESTEDHVM_PAGEFAULT_DONE;
}
diff -r 2115801e8e47 -r 80e00ac43548 xen/arch/x86/mm/mm-locks.h
--- a/xen/arch/x86/mm/mm-locks.h Thu Jun 30 10:26:54 2011 +0100
+++ b/xen/arch/x86/mm/mm-locks.h Thu Jun 30 10:26:54 2011 +0100
@@ -96,8 +96,11 @@
/* Nested P2M lock (per-domain)
*
- * A per-domain lock that protects some of the nested p2m datastructures.
- * TODO: find out exactly what needs to be covered by this lock */
+ * A per-domain lock that protects the mapping from nested-CR3 to
+ * nested-p2m. In particular it covers:
+ * - the array of nested-p2m tables, and all LRU activity therein; and
+ * - setting the "cr3" field of any p2m table to a non-CR3_EADDR value.
+ * (i.e. assigning a p2m table to be the shadow of that cr3 */
declare_mm_lock(nestedp2m)
#define nestedp2m_lock(d) mm_lock(nestedp2m, &(d)->arch.nested_p2m_lock)
diff -r 2115801e8e47 -r 80e00ac43548 xen/arch/x86/mm/p2m.c
--- a/xen/arch/x86/mm/p2m.c Thu Jun 30 10:26:54 2011 +0100
+++ b/xen/arch/x86/mm/p2m.c Thu Jun 30 10:26:54 2011 +0100
@@ -1052,7 +1052,7 @@
/* Reset this p2m table to be empty */
static void
-p2m_flush_locked(struct p2m_domain *p2m)
+p2m_flush_table(struct p2m_domain *p2m)
{
struct page_info *top, *pg;
struct domain *d = p2m->domain;
@@ -1094,21 +1094,16 @@
ASSERT(v->domain == d);
vcpu_nestedhvm(v).nv_p2m = NULL;
- nestedp2m_lock(d);
- p2m_flush_locked(p2m);
+ p2m_flush_table(p2m);
hvm_asid_flush_vcpu(v);
- nestedp2m_unlock(d);
}
void
p2m_flush_nestedp2m(struct domain *d)
{
int i;
-
- nestedp2m_lock(d);
for ( i = 0; i < MAX_NESTEDP2M; i++ )
- p2m_flush_locked(d->arch.nested_p2m[i]);
- nestedp2m_unlock(d);
+ p2m_flush_table(d->arch.nested_p2m[i]);
}
struct p2m_domain *
@@ -1131,29 +1126,37 @@
d = v->domain;
nestedp2m_lock(d);
p2m = nv->nv_p2m;
- if ( p2m && (p2m->cr3 == cr3 || p2m->cr3 == CR3_EADDR) )
+ if ( p2m )
{
- nv->nv_flushp2m = 0;
- p2m_getlru_nestedp2m(d, p2m);
- nv->nv_p2m = p2m;
- if (p2m->cr3 == CR3_EADDR)
- hvm_asid_flush_vcpu(v);
- p2m->cr3 = cr3;
- cpu_set(v->processor, p2m->p2m_dirty_cpumask);
- nestedp2m_unlock(d);
- return p2m;
+ p2m_lock(p2m);
+ if ( p2m->cr3 == cr3 || p2m->cr3 == CR3_EADDR )
+ {
+ nv->nv_flushp2m = 0;
+ p2m_getlru_nestedp2m(d, p2m);
+ nv->nv_p2m = p2m;
+ if (p2m->cr3 == CR3_EADDR)
+ hvm_asid_flush_vcpu(v);
+ p2m->cr3 = cr3;
+ cpu_set(v->processor, p2m->p2m_dirty_cpumask);
+ p2m_unlock(p2m);
+ nestedp2m_unlock(d);
+ return p2m;
+ }
+ p2m_unlock(p2m);
}
/* All p2m's are or were in use. Take the least recent used one,
* flush it and reuse. */
p2m = p2m_getlru_nestedp2m(d, NULL);
- p2m_flush_locked(p2m);
+ p2m_flush_table(p2m);
+ p2m_lock(p2m);
nv->nv_p2m = p2m;
p2m->cr3 = cr3;
nv->nv_flushp2m = 0;
hvm_asid_flush_vcpu(v);
- nestedhvm_vmcx_flushtlb(nv->nv_p2m);
+ nestedhvm_vmcx_flushtlb(p2m);
cpu_set(v->processor, p2m->p2m_dirty_cpumask);
+ p2m_unlock(p2m);
nestedp2m_unlock(d);
return p2m;
diff -r 2115801e8e47 -r 80e00ac43548 xen/include/asm-x86/p2m.h
--- a/xen/include/asm-x86/p2m.h Thu Jun 30 10:26:54 2011 +0100
+++ b/xen/include/asm-x86/p2m.h Thu Jun 30 10:26:54 2011 +0100
@@ -201,8 +201,13 @@
cpumask_t p2m_dirty_cpumask;
struct domain *domain; /* back pointer to domain */
+
+ /* Nested p2ms only: nested-CR3 value that this p2m shadows.
+ * This can be cleared to CR3_EADDR under the per-p2m lock but
+ * needs both the per-p2m lock and the per-domain nestedp2m lock
+ * to set it to any other value. */
#define CR3_EADDR (~0ULL)
- uint64_t cr3; /* to identify this p2m for re-use */
+ uint64_t cr3;
/* Pages used to construct the p2m */
struct page_list_head pages;
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