* [PATCH][3/4] Enable 1GB for Xen HVM host page
@ 2010-02-22 17:18 Wei Huang
2010-02-23 10:07 ` Tim Deegan
0 siblings, 1 reply; 5+ messages in thread
From: Wei Huang @ 2010-02-22 17:18 UTC (permalink / raw)
To: 'xen-devel@lists.xensource.com', Keir Fraser,
Xu, Dongxiao
[-- Attachment #1: Type: text/plain, Size: 151 bytes --]
This patch changes P2M code to works with 1GB page now.
Signed-off-by: Wei Huang <wei.huang2@amd.com>
Acked-by: Dongxiao Xu <dongxiao.xu@intel.com>
[-- Attachment #2: 3-xen-hap-fix-p2m.patch --]
[-- Type: text/x-patch, Size: 11909 bytes --]
# HG changeset patch
# User huangwei@huangwei.amd.com
# Date 1266853453 21600
# Node ID 72075d4fc39e8cd11a06bff4eb66521ab8fe952b
# Parent c9b45664b423e11003358944bb8e6e976e735301
fix p2m code to support 1GB pages
diff -r c9b45664b423 -r 72075d4fc39e xen/arch/x86/mm/p2m.c
--- a/xen/arch/x86/mm/p2m.c Mon Feb 22 09:44:09 2010 -0600
+++ b/xen/arch/x86/mm/p2m.c Mon Feb 22 09:44:13 2010 -0600
@@ -187,7 +187,36 @@
ASSERT(l1e_get_flags(*p2m_entry) & (_PAGE_PRESENT|_PAGE_PSE));
- /* split single large page into 4KB page in P2M table */
+ /* split 1GB pages into 2MB pages */
+ if ( type == PGT_l2_page_table && (l1e_get_flags(*p2m_entry) & _PAGE_PSE) )
+ {
+ unsigned long flags, pfn;
+ struct page_info *pg = d->arch.p2m->alloc_page(d);
+ if ( pg == NULL )
+ return 0;
+ page_list_add_tail(pg, &d->arch.p2m->pages);
+ pg->u.inuse.type_info = PGT_l2_page_table | 1 | PGT_validated;
+ pg->count_info = 1;
+
+ flags = l1e_get_flags(*p2m_entry);
+ pfn = l1e_get_pfn(*p2m_entry);
+
+ l1_entry = map_domain_page(mfn_x(page_to_mfn(pg)));
+ for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ )
+ {
+ new_entry = l1e_from_pfn(pfn + (i * L1_PAGETABLE_ENTRIES), flags);
+ paging_write_p2m_entry(d, gfn, l1_entry+i, *table_mfn, new_entry,
+ 2);
+ }
+ unmap_domain_page(l1_entry);
+ new_entry = l1e_from_pfn(mfn_x(page_to_mfn(pg)),
+ __PAGE_HYPERVISOR|_PAGE_USER); //disable PSE
+ paging_write_p2m_entry(d, gfn,
+ p2m_entry, *table_mfn, new_entry, 3);
+ }
+
+
+ /* split single 2MB large page into 4KB page in P2M table */
if ( type == PGT_l1_page_table && (l1e_get_flags(*p2m_entry) & _PAGE_PSE) )
{
unsigned long flags, pfn;
@@ -1064,6 +1093,19 @@
if ( unlikely(d->is_dying) )
goto out_fail;
+ /* Because PoD does not have cache list for 1GB pages, it has to remap
+ * 1GB region to 2MB chunks for a retry. */
+ if ( order == 18 )
+ {
+ gfn_aligned = (gfn >> order) << order;
+ for( i = 0; i < (1 << order); i += (1 << 9) )
+ set_p2m_entry(d, gfn_aligned + i, _mfn(POPULATE_ON_DEMAND_MFN), 9,
+ p2m_populate_on_demand);
+ audit_p2m(d);
+ p2m_unlock(p2md);
+ return 0;
+ }
+
/* If we're low, start a sweep */
if ( order == 9 && page_list_empty(&p2md->pod.super) )
p2m_pod_emergency_sweep_super(d);
@@ -1196,6 +1238,7 @@
l1_pgentry_t *p2m_entry;
l1_pgentry_t entry_content;
l2_pgentry_t l2e_content;
+ l3_pgentry_t l3e_content;
int rv=0;
if ( tb_init_done )
@@ -1222,18 +1265,44 @@
goto out;
#endif
/*
+ * Try to allocate 1GB page table if this feature is supported.
+ *
* When using PAE Xen, we only allow 33 bits of pseudo-physical
* address in translated guests (i.e. 8 GBytes). This restriction
* comes from wanting to map the P2M table into the 16MB RO_MPT hole
* in Xen's address space for translated PV guests.
* When using AMD's NPT on PAE Xen, we are restricted to 4GB.
*/
- if ( !p2m_next_level(d, &table_mfn, &table, &gfn_remainder, gfn,
- L3_PAGETABLE_SHIFT - PAGE_SHIFT,
- ((CONFIG_PAGING_LEVELS == 3)
- ? (d->arch.hvm_domain.hap_enabled ? 4 : 8)
- : L3_PAGETABLE_ENTRIES),
- PGT_l2_page_table) )
+ if ( page_order == 18 )
+ {
+ p2m_entry = p2m_find_entry(table, &gfn_remainder, gfn,
+ L3_PAGETABLE_SHIFT - PAGE_SHIFT,
+ L3_PAGETABLE_ENTRIES);
+ ASSERT(p2m_entry);
+ if ( (l1e_get_flags(*p2m_entry) & _PAGE_PRESENT) &&
+ !(l1e_get_flags(*p2m_entry) & _PAGE_PSE) )
+ {
+ P2M_ERROR("configure P2M table L3 entry with large page\n");
+ domain_crash(d);
+ goto out;
+ }
+
+ if ( mfn_valid(mfn) )
+ l3e_content = l3e_from_pfn(mfn_x(mfn),
+ p2m_type_to_flags(p2mt) | _PAGE_PSE);
+ else
+ l3e_content = l3e_empty();
+
+ entry_content.l1 = l3e_content.l3;
+ paging_write_p2m_entry(d, gfn, p2m_entry, table_mfn, entry_content, 3);
+
+ }
+ else if ( !p2m_next_level(d, &table_mfn, &table, &gfn_remainder, gfn,
+ L3_PAGETABLE_SHIFT - PAGE_SHIFT,
+ ((CONFIG_PAGING_LEVELS == 3)
+ ? (d->arch.hvm_domain.hap_enabled ? 4 : 8)
+ : L3_PAGETABLE_ENTRIES),
+ PGT_l2_page_table) )
goto out;
if ( page_order == 0 )
@@ -1255,7 +1324,7 @@
/* level 1 entry */
paging_write_p2m_entry(d, gfn, p2m_entry, table_mfn, entry_content, 1);
}
- else
+ else if ( page_order == 9 )
{
p2m_entry = p2m_find_entry(table, &gfn_remainder, gfn,
L2_PAGETABLE_SHIFT - PAGE_SHIFT,
@@ -1352,11 +1421,34 @@
#else
l3e += l3_table_offset(addr);
#endif
+pod_retry_l3:
if ( (l3e_get_flags(*l3e) & _PAGE_PRESENT) == 0 )
{
+ if ( p2m_flags_to_type(l3e_get_flags(*l3e)) == p2m_populate_on_demand )
+ {
+ if ( q != p2m_query )
+ {
+ if ( !p2m_pod_demand_populate(d, gfn, 18, q) )
+ goto pod_retry_l3;
+ }
+ else
+ *t = p2m_populate_on_demand;
+ }
unmap_domain_page(l3e);
return _mfn(INVALID_MFN);
}
+ else if ( (l3e_get_flags(*l3e) & _PAGE_PSE) )
+ {
+ mfn = _mfn(l3e_get_pfn(*l3e) +
+ l2_table_offset(addr) * L1_PAGETABLE_ENTRIES +
+ l1_table_offset(addr));
+ *t = p2m_flags_to_type(l3e_get_flags(*l3e));
+ unmap_domain_page(l3e);
+
+ ASSERT(mfn_valid(mfn) || !p2m_is_ram(*t));
+ return (p2m_is_valid(*t)) ? mfn : _mfn(INVALID_MFN);
+ }
+
mfn = _mfn(l3e_get_pfn(*l3e));
unmap_domain_page(l3e);
}
@@ -1437,10 +1529,57 @@
{
l1_pgentry_t l1e = l1e_empty(), *p2m_entry;
l2_pgentry_t l2e = l2e_empty();
+ l3_pgentry_t l3e = l3e_empty();
int ret;
ASSERT(gfn < (RO_MPT_VIRT_END - RO_MPT_VIRT_START)
/ sizeof(l1_pgentry_t));
+
+ /*
+ * Read & process L3
+ */
+ p2m_entry = (l1_pgentry_t *)
+ &__linear_l2_table[l2_linear_offset(RO_MPT_VIRT_START)
+ + l3_linear_offset(addr)];
+ pod_retry_l3:
+ ret = __copy_from_user(&l3e, p2m_entry, sizeof(l3e));
+
+ if ( ret != 0 || !(l3e_get_flags(l3e) & _PAGE_PRESENT) )
+ {
+ if ( (l3e_get_flags(l3e) & _PAGE_PSE) &&
+ (p2m_flags_to_type(l3e_get_flags(l3e)) == p2m_populate_on_demand) )
+ {
+ /* The read has succeeded, so we know that mapping exists */
+ if ( q != p2m_query )
+ {
+ if ( !p2m_pod_demand_populate(current->domain, gfn, 18, q) )
+ goto pod_retry_l3;
+ p2mt = p2m_invalid;
+ printk("%s: Allocate 1GB failed!\n", __func__);
+ goto out;
+ }
+ else
+ {
+ p2mt = p2m_populate_on_demand;
+ goto out;
+ }
+ }
+ goto pod_retry_l2;
+ }
+
+ if ( l3e_get_flags(l3e) & _PAGE_PSE )
+ {
+ p2mt = p2m_flags_to_type(l3e_get_flags(l3e));
+ ASSERT(l3e_get_pfn(l3e) != INVALID_MFN || !p2m_is_ram(p2mt));
+ if (p2m_is_valid(p2mt) )
+ mfn = _mfn(l3e_get_pfn(l3e) +
+ l2_table_offset(addr) * L1_PAGETABLE_ENTRIES +
+ l1_table_offset(addr));
+ else
+ p2mt = p2m_mmio_dm;
+
+ goto out;
+ }
/*
* Read & process L2
@@ -1596,8 +1735,10 @@
while ( todo )
{
if ( is_hvm_domain(d) && d->arch.hvm_domain.hap_enabled )
- order = (((gfn | mfn_x(mfn) | todo) & (SUPERPAGE_PAGES - 1)) == 0) ?
- 9 : 0;
+ order = ( (((gfn | mfn_x(mfn) | todo) & ((1ul << 18) - 1)) == 0) ) ?
+ 18 :
+ (((gfn | mfn_x(mfn) | todo) & ((1ul << 9) - 1)) == 0) ? 9 : 0;
+
else
order = 0;
if ( !d->arch.p2m->set_entry(d, gfn, mfn, order, p2mt) )
@@ -1867,6 +2008,31 @@
gfn += 1 << (L3_PAGETABLE_SHIFT - PAGE_SHIFT);
continue;
}
+
+ /* check for 1GB super page */
+ if ( l3e_get_flags(l3e[i3]) & _PAGE_PSE )
+ {
+ mfn = l3e_get_pfn(l3e[i3]);
+ ASSERT(mfn_valid(_mfn(mfn)));
+ /* we have to cover 512x512 4K pages */
+ for ( i2 = 0;
+ i2 < (L2_PAGETABLE_ENTRIES * L1_PAGETABLE_ENTRIES);
+ i2++)
+ {
+ m2pfn = get_gpfn_from_mfn(mfn+i2);
+ if ( m2pfn != (gfn + i2) )
+ {
+ pmbad++;
+ P2M_PRINTK("mismatch: gfn %#lx -> mfn %#lx"
+ " -> gfn %#lx\n", gfn+i2, mfn+i2,
+ m2pfn);
+ BUG();
+ }
+ gfn += 1 << (L3_PAGETABLE_SHIFT - PAGE_SHIFT);
+ continue;
+ }
+ }
+
l2e = map_domain_page(mfn_x(_mfn(l3e_get_pfn(l3e[i3]))));
for ( i2 = 0; i2 < L2_PAGETABLE_ENTRIES; i2++ )
{
@@ -2224,7 +2390,7 @@
l1_pgentry_t l1e_content;
l1_pgentry_t *l1e;
l2_pgentry_t *l2e;
- mfn_t l1mfn, l2mfn;
+ mfn_t l1mfn, l2mfn, l3mfn;
unsigned long i1, i2, i3;
l3_pgentry_t *l3e;
#if CONFIG_PAGING_LEVELS == 4
@@ -2245,6 +2411,7 @@
#if CONFIG_PAGING_LEVELS == 4
l4e = map_domain_page(mfn_x(pagetable_get_mfn(d->arch.phys_table)));
#else /* CONFIG_PAGING_LEVELS == 3 */
+ l3mfn = _mfn(mfn_x(pagetable_get_mfn(d->arch.phys_table)));
l3e = map_domain_page(mfn_x(pagetable_get_mfn(d->arch.phys_table)));
#endif
@@ -2255,6 +2422,7 @@
{
continue;
}
+ l3mfn = _mfn(l4e_get_pfn(l4e[i4]));
l3e = map_domain_page(l4e_get_pfn(l4e[i4]));
#endif
for ( i3 = 0;
@@ -2265,6 +2433,20 @@
{
continue;
}
+ if ( (l3e_get_flags(l3e[i3]) & _PAGE_PSE) )
+ {
+ flags = l3e_get_flags(l3e[i3]);
+ if ( p2m_flags_to_type(flags) != ot )
+ continue;
+ mfn = l3e_get_pfn(l3e[i3]);
+ gfn = get_gpfn_from_mfn(mfn);
+ flags = p2m_type_to_flags(nt);
+ l1e_content = l1e_from_pfn(mfn, flags | _PAGE_PSE);
+ paging_write_p2m_entry(d, gfn, (l1_pgentry_t *)&l3e[i3],
+ l3mfn, l1e_content, 3);
+ continue;
+ }
+
l2mfn = _mfn(l3e_get_pfn(l3e[i3]));
l2e = map_domain_page(l3e_get_pfn(l3e[i3]));
for ( i2 = 0; i2 < L2_PAGETABLE_ENTRIES; i2++ )
[-- Attachment #3: Type: text/plain, Size: 138 bytes --]
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http://lists.xensource.com/xen-devel
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH][3/4] Enable 1GB for Xen HVM host page
2010-02-22 17:18 [PATCH][3/4] Enable 1GB for Xen HVM host page Wei Huang
@ 2010-02-23 10:07 ` Tim Deegan
2010-02-23 16:37 ` Huang2, Wei
0 siblings, 1 reply; 5+ messages in thread
From: Tim Deegan @ 2010-02-23 10:07 UTC (permalink / raw)
To: Wei Huang
Cc: Keir, Xu, Dongxiao, 'xen-devel@lists.xensource.com',
Fraser
At 17:18 +0000 on 22 Feb (1266859128), Wei Huang wrote:
> This patch changes P2M code to works with 1GB page now.
>
> Signed-off-by: Wei Huang <wei.huang2@amd.com>
> Acked-by: Dongxiao Xu <dongxiao.xu@intel.com>
> @@ -1064,6 +1093,19 @@
> if ( unlikely(d->is_dying) )
> goto out_fail;
>
> + /* Because PoD does not have cache list for 1GB pages, it has to remap
> + * 1GB region to 2MB chunks for a retry. */
> + if ( order == 18 )
> + {
> + gfn_aligned = (gfn >> order) << order;
> + for( i = 0; i < (1 << order); i += (1 << 9) )
> + set_p2m_entry(d, gfn_aligned + i, _mfn(POPULATE_ON_DEMAND_MFN), 9,
> + p2m_populate_on_demand);
I think you only need one set_p2m_entry call here - it will split the
1GB entry without needing another 511 calls.
Was the decision not to implement populate-on-demand for 1GB pages based
on not thinking it's a good idea or not wanting to do the work? :)
How much performance do PoD guests lose by not having it?
> + audit_p2m(d);
> + p2m_unlock(p2md);
> + return 0;
> + }
> +
> /* If we're low, start a sweep */
> if ( order == 9 && page_list_empty(&p2md->pod.super) )
> p2m_pod_emergency_sweep_super(d);
> @@ -1196,6 +1238,7 @@
> l1_pgentry_t *p2m_entry;
> l1_pgentry_t entry_content;
> l2_pgentry_t l2e_content;
> + l3_pgentry_t l3e_content;
> int rv=0;
>
> if ( tb_init_done )
> @@ -1222,18 +1265,44 @@
> goto out;
> #endif
> /*
> + * Try to allocate 1GB page table if this feature is supported.
> + *
> * When using PAE Xen, we only allow 33 bits of pseudo-physical
> * address in translated guests (i.e. 8 GBytes). This restriction
> * comes from wanting to map the P2M table into the 16MB RO_MPT hole
> * in Xen's address space for translated PV guests.
> * When using AMD's NPT on PAE Xen, we are restricted to 4GB.
> */
Please move this comment closer to the code it describes.
Also maybe a BUG_ON(CONFIG_PAGING_LEVELS == 3) in the order-18 case
would be useful, since otherwise it looks like order-18 allocations are
exempt from the restriction.
Actually, I don't see where you enforce that - do you?
Tim.
--
Tim Deegan <Tim.Deegan@citrix.com>
Principal Software Engineer, XenServer Engineering
Citrix Systems UK Ltd. (Company #02937203, SL9 0BG)
^ permalink raw reply [flat|nested] 5+ messages in thread
* RE: [PATCH][3/4] Enable 1GB for Xen HVM host page
2010-02-23 10:07 ` Tim Deegan
@ 2010-02-23 16:37 ` Huang2, Wei
2010-02-24 9:13 ` Tim Deegan
0 siblings, 1 reply; 5+ messages in thread
From: Huang2, Wei @ 2010-02-23 16:37 UTC (permalink / raw)
To: Tim Deegan
Cc: Keir, Xu, Dongxiao, 'xen-devel@lists.xensource.com',
Fraser
I was hoping that someone else would pick up the 1GB PoD task. :P I can try to implement this feature if deemed necessary.
-Wei
-----Original Message-----
From: Tim Deegan [mailto:Tim.Deegan@citrix.com]
Sent: Tuesday, February 23, 2010 4:07 AM
To: Huang2, Wei
Cc: 'xen-devel@lists.xensource.com'; Keir Fraser; Xu, Dongxiao
Subject: Re: [Xen-devel] [PATCH][3/4] Enable 1GB for Xen HVM host page
At 17:18 +0000 on 22 Feb (1266859128), Wei Huang wrote:
> This patch changes P2M code to works with 1GB page now.
>
> Signed-off-by: Wei Huang <wei.huang2@amd.com>
> Acked-by: Dongxiao Xu <dongxiao.xu@intel.com>
> @@ -1064,6 +1093,19 @@
> if ( unlikely(d->is_dying) )
> goto out_fail;
>
> + /* Because PoD does not have cache list for 1GB pages, it has to remap
> + * 1GB region to 2MB chunks for a retry. */
> + if ( order == 18 )
> + {
> + gfn_aligned = (gfn >> order) << order;
> + for( i = 0; i < (1 << order); i += (1 << 9) )
> + set_p2m_entry(d, gfn_aligned + i, _mfn(POPULATE_ON_DEMAND_MFN), 9,
> + p2m_populate_on_demand);
I think you only need one set_p2m_entry call here - it will split the
1GB entry without needing another 511 calls.
Was the decision not to implement populate-on-demand for 1GB pages based
on not thinking it's a good idea or not wanting to do the work? :)
How much performance do PoD guests lose by not having it?
> + audit_p2m(d);
> + p2m_unlock(p2md);
> + return 0;
> + }
> +
> /* If we're low, start a sweep */
> if ( order == 9 && page_list_empty(&p2md->pod.super) )
> p2m_pod_emergency_sweep_super(d);
> @@ -1196,6 +1238,7 @@
> l1_pgentry_t *p2m_entry;
> l1_pgentry_t entry_content;
> l2_pgentry_t l2e_content;
> + l3_pgentry_t l3e_content;
> int rv=0;
>
> if ( tb_init_done )
> @@ -1222,18 +1265,44 @@
> goto out;
> #endif
> /*
> + * Try to allocate 1GB page table if this feature is supported.
> + *
> * When using PAE Xen, we only allow 33 bits of pseudo-physical
> * address in translated guests (i.e. 8 GBytes). This restriction
> * comes from wanting to map the P2M table into the 16MB RO_MPT hole
> * in Xen's address space for translated PV guests.
> * When using AMD's NPT on PAE Xen, we are restricted to 4GB.
> */
Please move this comment closer to the code it describes.
Also maybe a BUG_ON(CONFIG_PAGING_LEVELS == 3) in the order-18 case
would be useful, since otherwise it looks like order-18 allocations are
exempt from the restriction.
Actually, I don't see where you enforce that - do you?
Tim.
--
Tim Deegan <Tim.Deegan@citrix.com>
Principal Software Engineer, XenServer Engineering
Citrix Systems UK Ltd. (Company #02937203, SL9 0BG)
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH][3/4] Enable 1GB for Xen HVM host page
2010-02-23 16:37 ` Huang2, Wei
@ 2010-02-24 9:13 ` Tim Deegan
2010-02-25 10:30 ` George Dunlap
0 siblings, 1 reply; 5+ messages in thread
From: Tim Deegan @ 2010-02-24 9:13 UTC (permalink / raw)
To: Huang2, Wei
Cc: Keir, Xu, Dongxiao, 'xen-devel@lists.xensource.com',
Fraser
At 16:37 +0000 on 23 Feb (1266943030), Huang2, Wei wrote:
> I was hoping that someone else would pick up the 1GB PoD task. :P I
> can try to implement this feature if deemed necessary.
I think it will be OK - PoD is only useful with balloon drivers, which
currently don't even maintain 2MB superpages, so it's probably not worth
engineering up 1GB PoD.
Tim.
> -Wei
>
> -----Original Message-----
> From: Tim Deegan [mailto:Tim.Deegan@citrix.com]
> Sent: Tuesday, February 23, 2010 4:07 AM
> To: Huang2, Wei
> Cc: 'xen-devel@lists.xensource.com'; Keir Fraser; Xu, Dongxiao
> Subject: Re: [Xen-devel] [PATCH][3/4] Enable 1GB for Xen HVM host page
>
> At 17:18 +0000 on 22 Feb (1266859128), Wei Huang wrote:
> > This patch changes P2M code to works with 1GB page now.
> >
> > Signed-off-by: Wei Huang <wei.huang2@amd.com>
> > Acked-by: Dongxiao Xu <dongxiao.xu@intel.com>
>
>
> > @@ -1064,6 +1093,19 @@
> > if ( unlikely(d->is_dying) )
> > goto out_fail;
> >
> > + /* Because PoD does not have cache list for 1GB pages, it has to remap
> > + * 1GB region to 2MB chunks for a retry. */
> > + if ( order == 18 )
> > + {
> > + gfn_aligned = (gfn >> order) << order;
> > + for( i = 0; i < (1 << order); i += (1 << 9) )
> > + set_p2m_entry(d, gfn_aligned + i, _mfn(POPULATE_ON_DEMAND_MFN), 9,
> > + p2m_populate_on_demand);
>
> I think you only need one set_p2m_entry call here - it will split the
> 1GB entry without needing another 511 calls.
>
> Was the decision not to implement populate-on-demand for 1GB pages based
> on not thinking it's a good idea or not wanting to do the work? :)
> How much performance do PoD guests lose by not having it?
>
> > + audit_p2m(d);
> > + p2m_unlock(p2md);
> > + return 0;
> > + }
> > +
> > /* If we're low, start a sweep */
> > if ( order == 9 && page_list_empty(&p2md->pod.super) )
> > p2m_pod_emergency_sweep_super(d);
> > @@ -1196,6 +1238,7 @@
> > l1_pgentry_t *p2m_entry;
> > l1_pgentry_t entry_content;
> > l2_pgentry_t l2e_content;
> > + l3_pgentry_t l3e_content;
> > int rv=0;
> >
> > if ( tb_init_done )
> > @@ -1222,18 +1265,44 @@
> > goto out;
> > #endif
> > /*
> > + * Try to allocate 1GB page table if this feature is supported.
> > + *
> > * When using PAE Xen, we only allow 33 bits of pseudo-physical
> > * address in translated guests (i.e. 8 GBytes). This restriction
> > * comes from wanting to map the P2M table into the 16MB RO_MPT hole
> > * in Xen's address space for translated PV guests.
> > * When using AMD's NPT on PAE Xen, we are restricted to 4GB.
> > */
>
> Please move this comment closer to the code it describes.
>
> Also maybe a BUG_ON(CONFIG_PAGING_LEVELS == 3) in the order-18 case
> would be useful, since otherwise it looks like order-18 allocations are
> exempt from the restriction.
>
> Actually, I don't see where you enforce that - do you?
>
> Tim.
>
>
> --
> Tim Deegan <Tim.Deegan@citrix.com>
> Principal Software Engineer, XenServer Engineering
> Citrix Systems UK Ltd. (Company #02937203, SL9 0BG)
>
>
--
Tim Deegan <Tim.Deegan@citrix.com>
Principal Software Engineer, XenServer Engineering
Citrix Systems UK Ltd. (Company #02937203, SL9 0BG)
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH][3/4] Enable 1GB for Xen HVM host page
2010-02-24 9:13 ` Tim Deegan
@ 2010-02-25 10:30 ` George Dunlap
0 siblings, 0 replies; 5+ messages in thread
From: George Dunlap @ 2010-02-25 10:30 UTC (permalink / raw)
To: Tim Deegan
Cc: Xu, Dongxiao, Huang2, Wei, xen-devel@lists.xensource.com, Fraser
On Wed, Feb 24, 2010 at 9:13 AM, Tim Deegan <Tim.Deegan@citrix.com> wrote:
> At 16:37 +0000 on 23 Feb (1266943030), Huang2, Wei wrote:
>> I was hoping that someone else would pick up the 1GB PoD task. :P I
>> can try to implement this feature if deemed necessary.
>
> I think it will be OK - PoD is only useful with balloon drivers, which
> currently don't even maintain 2MB superpages, so it's probably not worth
> engineering up 1GB PoD.
Agreed. As long as everything still functions properly when PoD is
turned on, not having 1G PoD entries shouldn't be a big priority.
-George
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2010-02-25 10:30 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2010-02-22 17:18 [PATCH][3/4] Enable 1GB for Xen HVM host page Wei Huang
2010-02-23 10:07 ` Tim Deegan
2010-02-23 16:37 ` Huang2, Wei
2010-02-24 9:13 ` Tim Deegan
2010-02-25 10:30 ` George Dunlap
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