|
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] Ping: [PATCH] x86/mm: re-arrange get_page_from_l<N>e() vs pv_l1tf_check_l<N>e
>>> On 17.08.18 at 08:42, wrote:
> Restore symmetry between get_page_from_l<N>e(): pv_l1tf_check_l<N>e is
> 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.
>
> 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@xxxxxxxx>
>
> --- a/xen/arch/x86/mm.c
> +++ b/xen/arch/x86/mm.c
> @@ -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_in
> 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_in
>
> 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_in
> 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_in
> 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_in
> 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_in
> 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_in
> }
>
> 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_in
> 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_in
> 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);
>
> --- a/xen/arch/x86/pv/ro-page-fault.c
> +++ b/xen/arch/x86/pv/ro-page-fault.c
> @@ -131,10 +131,12 @@ static int ptwr_emulated_update(unsigned
> /* 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) &&
>
>
>
>
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel
|
 |
Lists.xenproject.org is hosted with RackSpace, monitoring our |