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x86/mm: re-arrange get_page_from_l<N>e() vs pv_l1tf_check_l<N>e()

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Restore symmetry between get_page_from_l<N>e(): pv_l1tf_check_l<N>e() is
now uniformly invoked from outside of them. They're no longer getting
called for non-present PTEs. This way the slightly odd three-way return
value meaning of the higher level ones can also be got rid of.

Leave an assertion in get_page_from_l1e() as the only non-static one of
the four siblings, to ensure that no new unguarded calls go unnoticed.

Introduce local variables holding the page table entries processed, and
use them throughout the loop bodies instead of re-reading them from the
page table several times.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
This commit is contained in:
Jan Beulich committed 2018-08-30 11:01:02 +02:00
1 parent aed19fb537
commit 3ac0b20bc3
2 files changed
+60 -55
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xen/arch/x86/mm.c
+54 -51
View File
@@ -900,8 +900,11 @@ get_page_from_l1e(
struct domain *real_pg_owner;
bool write;
if ( !(l1f & _PAGE_PRESENT) )
if ( unlikely(!(l1f & _PAGE_PRESENT)) )
{
ASSERT_UNREACHABLE();
return 0;
}
if ( unlikely(l1f & l1_disallow_mask(l1e_owner)) )
{
@@ -1099,14 +1102,6 @@ get_page_from_l1e(
return -EBUSY;
}
/* NB. Virtual address 'l2e' maps to a machine address within frame 'pfn'. */
/*
* get_page_from_l2e returns:
* 1 => page not present
* 0 => success
* <0 => error code
*/
define_get_linear_pagetable(l2);
static int
get_page_from_l2e(
@@ -1115,9 +1110,6 @@ get_page_from_l2e(
unsigned long mfn = l2e_get_pfn(l2e);
int rc;
if ( !(l2e_get_flags(l2e) & _PAGE_PRESENT) )
return pv_l1tf_check_l2e(d, l2e) ? -ERESTART : 1;
if ( unlikely((l2e_get_flags(l2e) & L2_DISALLOW_MASK)) )
{
gdprintk(XENLOG_WARNING, "Bad L2 flags %x\n",
@@ -1132,13 +1124,6 @@ get_page_from_l2e(
return rc;
}
/*
* get_page_from_l3e returns:
* 1 => page not present
* 0 => success
* <0 => error code
*/
define_get_linear_pagetable(l3);
static int
get_page_from_l3e(
@@ -1146,9 +1131,6 @@ get_page_from_l3e(
{
int rc;
if ( !(l3e_get_flags(l3e) & _PAGE_PRESENT) )
return pv_l1tf_check_l3e(d, l3e) ? -ERESTART : 1;
if ( unlikely((l3e_get_flags(l3e) & l3_disallow_mask(d))) )
{
gdprintk(XENLOG_WARNING, "Bad L3 flags %x\n",
@@ -1166,12 +1148,6 @@ get_page_from_l3e(
return rc;
}
/*
* get_page_from_l4e returns:
* 1 => page not present
* 0 => success
* <0 => error code
*/
define_get_linear_pagetable(l4);
static int
get_page_from_l4e(
@@ -1179,9 +1155,6 @@ get_page_from_l4e(
{
int rc;
if ( !(l4e_get_flags(l4e) & _PAGE_PRESENT) )
return pv_l1tf_check_l4e(d, l4e) ? -ERESTART : 1;
if ( unlikely((l4e_get_flags(l4e) & L4_DISALLOW_MASK)) )
{
gdprintk(XENLOG_WARNING, "Bad L4 flags %x\n",
@@ -1396,8 +1369,7 @@ static int alloc_l1_table(struct page_info *page)
if ( ret )
goto out;
}
switch ( ret = get_page_from_l1e(pl1e[i], d, d) )
else switch ( ret = get_page_from_l1e(pl1e[i], d, d) )
{
default:
goto fail;
@@ -1477,6 +1449,8 @@ static int alloc_l2_table(struct page_info *page, unsigned long type)
for ( i = page->nr_validated_ptes; i < L2_PAGETABLE_ENTRIES; i++ )
{
l2_pgentry_t l2e;
if ( i > page->nr_validated_ptes && hypercall_preempt_check() )
{
page->nr_validated_ptes = i;
@@ -1484,10 +1458,20 @@ static int alloc_l2_table(struct page_info *page, unsigned long type)
break;
}
if ( !is_guest_l2_slot(d, type, i) ||
(rc = get_page_from_l2e(pl2e[i], pfn, d)) > 0 )
if ( !is_guest_l2_slot(d, type, i) )
continue;
l2e = pl2e[i];
if ( !(l2e_get_flags(l2e) & _PAGE_PRESENT) )
{
if ( !pv_l1tf_check_l2e(d, l2e) )
continue;
rc = -ERESTART;
}
else
rc = get_page_from_l2e(l2e, pfn, d);
if ( unlikely(rc == -ERESTART) )
{
page->nr_validated_ptes = i;
@@ -1503,14 +1487,14 @@ static int alloc_l2_table(struct page_info *page, unsigned long type)
break;
}
pl2e[i] = adjust_guest_l2e(pl2e[i], d);
pl2e[i] = adjust_guest_l2e(l2e, d);
}
if ( rc >= 0 && (type & PGT_pae_xen_l2) )
if ( !rc && (type & PGT_pae_xen_l2) )
init_xen_pae_l2_slots(pl2e, d);
unmap_domain_page(pl2e);
return rc > 0 ? 0 : rc;
return rc;
}
static int alloc_l3_table(struct page_info *page)
@@ -1536,18 +1520,26 @@ static int alloc_l3_table(struct page_info *page)
for ( i = page->nr_validated_ptes; i < L3_PAGETABLE_ENTRIES;
i++, partial = 0 )
{
l3_pgentry_t l3e = pl3e[i];
if ( is_pv_32bit_domain(d) && (i == 3) )
{
if ( !(l3e_get_flags(pl3e[i]) & _PAGE_PRESENT) ||
(l3e_get_flags(pl3e[i]) & l3_disallow_mask(d)) )
if ( !(l3e_get_flags(l3e) & _PAGE_PRESENT) ||
(l3e_get_flags(l3e) & l3_disallow_mask(d)) )
rc = -EINVAL;
else
rc = get_page_and_type_from_mfn(
l3e_get_mfn(pl3e[i]),
l3e_get_mfn(l3e),
PGT_l2_page_table | PGT_pae_xen_l2, d, partial, 1);
}
else if ( (rc = get_page_from_l3e(pl3e[i], pfn, d, partial)) > 0 )
continue;
else if ( !(l3e_get_flags(l3e) & _PAGE_PRESENT) )
{
if ( !pv_l1tf_check_l3e(d, l3e) )
continue;
rc = -ERESTART;
}
else
rc = get_page_from_l3e(l3e, pfn, d, partial);
if ( rc == -ERESTART )
{
@@ -1563,10 +1555,10 @@ static int alloc_l3_table(struct page_info *page)
if ( rc < 0 )
break;
pl3e[i] = adjust_guest_l3e(pl3e[i], d);
pl3e[i] = adjust_guest_l3e(l3e, d);
}
if ( rc >= 0 && !create_pae_xen_mappings(d, pl3e) )
if ( !rc && !create_pae_xen_mappings(d, pl3e) )
rc = -EINVAL;
if ( rc < 0 && rc != -ERESTART && rc != -EINTR )
{
@@ -1583,7 +1575,7 @@ static int alloc_l3_table(struct page_info *page)
}
unmap_domain_page(pl3e);
return rc > 0 ? 0 : rc;
return rc;
}
void init_xen_pae_l2_slots(l2_pgentry_t *l2t, const struct domain *d)
@@ -1711,10 +1703,22 @@ static int alloc_l4_table(struct page_info *page)
for ( i = page->nr_validated_ptes; i < L4_PAGETABLE_ENTRIES;
i++, partial = 0 )
{
if ( !is_guest_l4_slot(d, i) ||
(rc = get_page_from_l4e(pl4e[i], pfn, d, partial)) > 0 )
l4_pgentry_t l4e;
if ( !is_guest_l4_slot(d, i) )
continue;
l4e = pl4e[i];
if ( !(l4e_get_flags(l4e) & _PAGE_PRESENT) )
{
if ( !pv_l1tf_check_l4e(d, l4e) )
continue;
rc = -ERESTART;
}
else
rc = get_page_from_l4e(l4e, pfn, d, partial);
if ( rc == -ERESTART )
{
page->nr_validated_ptes = i;
@@ -1746,15 +1750,14 @@ static int alloc_l4_table(struct page_info *page)
return rc;
}
pl4e[i] = adjust_guest_l4e(pl4e[i], d);
pl4e[i] = adjust_guest_l4e(l4e, d);
}
if ( rc >= 0 )
if ( !rc )
{
init_xen_l4_slots(pl4e, _mfn(pfn),
d, INVALID_MFN, VM_ASSIST(d, m2p_strict));
atomic_inc(&d->arch.pv_domain.nr_l4_pages);
rc = 0;
}
unmap_domain_page(pl4e);
xen/arch/x86/pv/ro-page-fault.c
+6 -4
View File
@@ -131,10 +131,12 @@ static int ptwr_emulated_update(unsigned long addr, intpte_t *p_old,
/* Check the new PTE. */
nl1e = l1e_from_intpte(val);
if ( !(l1e_get_flags(nl1e) & _PAGE_PRESENT) && pv_l1tf_check_l1e(d, nl1e) )
return X86EMUL_RETRY;
switch ( ret = get_page_from_l1e(nl1e, d, d) )
if ( !(l1e_get_flags(nl1e) & _PAGE_PRESENT) )
{
if ( pv_l1tf_check_l1e(d, nl1e) )
return X86EMUL_RETRY;
}
else switch ( ret = get_page_from_l1e(nl1e, d, d) )
{
default:
if ( is_pv_32bit_domain(d) && (bytes == 4) && (unaligned_addr & 4) &&
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