* [Xen-devel] [PATCH v8 2/4] add a domain_tot_pages() helper function
2020-01-30 14:57 [Xen-devel] [PATCH v8 0/4] purge free_shared_domheap_page() Paul Durrant
2020-01-30 14:57 ` [Xen-devel] [PATCH v8 1/4] x86 / vmx: move teardown from domain_destroy() Paul Durrant
@ 2020-01-30 14:57 ` Paul Durrant
2020-01-30 16:29 ` Jan Beulich
2020-01-31 12:52 ` Jan Beulich
2020-01-30 14:57 ` [Xen-devel] [PATCH v8 3/4] mm: make pages allocated with MEMF_no_refcount safe to assign Paul Durrant
2020-01-30 14:57 ` [Xen-devel] [PATCH v8 4/4] x86 / vmx: use a MEMF_no_refcount domheap page for APIC_DEFAULT_PHYS_BASE Paul Durrant
3 siblings, 2 replies; 15+ messages in thread
From: Paul Durrant @ 2020-01-30 14:57 UTC (permalink / raw)
To: xen-devel
Cc: Stefano Stabellini, Julien Grall, Wei Liu, Konrad Rzeszutek Wilk,
George Dunlap, Andrew Cooper, Paul Durrant, Ian Jackson,
Tim Deegan, Roger Pau Monné
This patch adds a new domain_tot_pages() inline helper function into
sched.h, which will be needed by a subsequent patch.
No functional change.
NOTE: While modifying the comment for 'tot_pages' in sched.h this patch
makes some cosmetic fixes to surrounding comments.
Suggested-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
---
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Wei Liu <wl@xen.org>
Cc: "Roger Pau Monné" <roger.pau@citrix.com>
Cc: George Dunlap <George.Dunlap@eu.citrix.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Julien Grall <julien@xen.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: George Dunlap <george.dunlap@eu.citrix.com>
Cc: Tim Deegan <tim@xen.org>
v8:
- New in v8
---
xen/arch/x86/domain.c | 2 +-
xen/arch/x86/mm.c | 6 +++---
xen/arch/x86/mm/p2m-pod.c | 10 +++++-----
xen/arch/x86/mm/shadow/common.c | 2 +-
xen/arch/x86/msi.c | 2 +-
xen/arch/x86/numa.c | 2 +-
xen/arch/x86/pv/dom0_build.c | 25 +++++++++++++------------
xen/arch/x86/pv/domain.c | 2 +-
xen/common/domctl.c | 2 +-
xen/common/grant_table.c | 4 ++--
xen/common/keyhandler.c | 2 +-
xen/common/memory.c | 4 ++--
xen/common/page_alloc.c | 15 ++++++++-------
xen/include/public/memory.h | 4 ++--
xen/include/xen/sched.h | 24 ++++++++++++++++++------
15 files changed, 60 insertions(+), 46 deletions(-)
diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 28fefa1f81..643c23ffb0 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -218,7 +218,7 @@ void dump_pageframe_info(struct domain *d)
printk("Memory pages belonging to domain %u:\n", d->domain_id);
- if ( d->tot_pages >= 10 && d->is_dying < DOMDYING_dead )
+ if ( domain_tot_pages(d) >= 10 && d->is_dying < DOMDYING_dead )
{
printk(" DomPage list too long to display\n");
}
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index f50c065af3..8bb66cf30c 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -4194,8 +4194,8 @@ long do_mmu_update(
* - page caching attributes cleaned up
* - removed from the domain's page_list
*
- * If MEMF_no_refcount is not set, the domain's tot_pages will be
- * adjusted. If this results in the page count falling to 0,
+ * If MEMF_no_refcount is not set, the domain_adjust_tot_pages() will
+ * be called. If this results in the page count falling to 0,
* put_domain() will be called.
*
* The caller should either call free_domheap_page() to free the
@@ -4870,7 +4870,7 @@ long arch_memory_op(unsigned long cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
else if ( rc >= 0 )
{
p2m = p2m_get_hostp2m(d);
- target.tot_pages = d->tot_pages;
+ target.tot_pages = domain_tot_pages(d);
target.pod_cache_pages = p2m->pod.count;
target.pod_entries = p2m->pod.entry_count;
diff --git a/xen/arch/x86/mm/p2m-pod.c b/xen/arch/x86/mm/p2m-pod.c
index 096e2773fb..f2c9409568 100644
--- a/xen/arch/x86/mm/p2m-pod.c
+++ b/xen/arch/x86/mm/p2m-pod.c
@@ -302,7 +302,7 @@ out:
* The following equations should hold:
* 0 <= P <= T <= B <= M
* d->arch.p2m->pod.entry_count == B - P
- * d->tot_pages == P + d->arch.p2m->pod.count
+ * domain_tot_pages(d) == P + d->arch.p2m->pod.count
*
* Now we have the following potential cases to cover:
* B <T': Set the PoD cache size equal to the number of outstanding PoD
@@ -336,7 +336,7 @@ p2m_pod_set_mem_target(struct domain *d, unsigned long target)
pod_lock(p2m);
/* P == B: Nothing to do (unless the guest is being created). */
- populated = d->tot_pages - p2m->pod.count;
+ populated = domain_tot_pages(d) - p2m->pod.count;
if ( populated > 0 && p2m->pod.entry_count == 0 )
goto out;
@@ -348,7 +348,7 @@ p2m_pod_set_mem_target(struct domain *d, unsigned long target)
* T' < B: Don't reduce the cache size; let the balloon driver
* take care of it.
*/
- if ( target < d->tot_pages )
+ if ( target < domain_tot_pages(d) )
goto out;
pod_target = target - populated;
@@ -1231,8 +1231,8 @@ out_of_memory:
pod_unlock(p2m);
printk("%s: Dom%d out of PoD memory! (tot=%"PRIu32" ents=%ld dom%d)\n",
- __func__, d->domain_id, d->tot_pages, p2m->pod.entry_count,
- current->domain->domain_id);
+ __func__, d->domain_id, domain_tot_pages(d),
+ p2m->pod.entry_count, current->domain->domain_id);
domain_crash(d);
return false;
out_fail:
diff --git a/xen/arch/x86/mm/shadow/common.c b/xen/arch/x86/mm/shadow/common.c
index 6212ec2c4a..cba3ab1eba 100644
--- a/xen/arch/x86/mm/shadow/common.c
+++ b/xen/arch/x86/mm/shadow/common.c
@@ -1256,7 +1256,7 @@ static unsigned int sh_min_allocation(const struct domain *d)
* up of slot zero and an LAPIC page), plus one for HVM's 1-to-1 pagetable.
*/
return shadow_min_acceptable_pages(d) +
- max(max(d->tot_pages / 256,
+ max(max(domain_tot_pages(d) / 256,
is_hvm_domain(d) ? CONFIG_PAGING_LEVELS + 2 : 0U) +
is_hvm_domain(d),
d->arch.paging.shadow.p2m_pages);
diff --git a/xen/arch/x86/msi.c b/xen/arch/x86/msi.c
index df97ce0c72..2fabaaa155 100644
--- a/xen/arch/x86/msi.c
+++ b/xen/arch/x86/msi.c
@@ -991,7 +991,7 @@ static int msix_capability_init(struct pci_dev *dev,
seg, bus, slot, func, d->domain_id);
if ( !is_hardware_domain(d) &&
/* Assume a domain without memory has no mappings yet. */
- (!is_hardware_domain(currd) || d->tot_pages) )
+ (!is_hardware_domain(currd) || domain_tot_pages(d)) )
domain_crash(d);
/* XXX How to deal with existing mappings? */
}
diff --git a/xen/arch/x86/numa.c b/xen/arch/x86/numa.c
index 7e1f563012..7f0d27c153 100644
--- a/xen/arch/x86/numa.c
+++ b/xen/arch/x86/numa.c
@@ -419,7 +419,7 @@ static void dump_numa(unsigned char key)
{
process_pending_softirqs();
- printk("Domain %u (total: %u):\n", d->domain_id, d->tot_pages);
+ printk("Domain %u (total: %u):\n", d->domain_id, domain_tot_pages(d));
for_each_online_node ( i )
page_num_node[i] = 0;
diff --git a/xen/arch/x86/pv/dom0_build.c b/xen/arch/x86/pv/dom0_build.c
index 9a97cf4abf..5678da782d 100644
--- a/xen/arch/x86/pv/dom0_build.c
+++ b/xen/arch/x86/pv/dom0_build.c
@@ -110,8 +110,9 @@ static __init void setup_pv_physmap(struct domain *d, unsigned long pgtbl_pfn,
while ( vphysmap_start < vphysmap_end )
{
- if ( d->tot_pages + ((round_pgup(vphysmap_end) - vphysmap_start)
- >> PAGE_SHIFT) + 3 > nr_pages )
+ if ( domain_tot_pages(d) +
+ ((round_pgup(vphysmap_end) - vphysmap_start) >> PAGE_SHIFT) +
+ 3 > nr_pages )
panic("Dom0 allocation too small for initial P->M table\n");
if ( pl1e )
@@ -264,7 +265,7 @@ static struct page_info * __init alloc_chunk(struct domain *d,
{
struct page_info *pg2;
- if ( d->tot_pages + (1 << order) > d->max_pages )
+ if ( domain_tot_pages(d) + (1 << order) > d->max_pages )
continue;
pg2 = alloc_domheap_pages(d, order, MEMF_exact_node | MEMF_no_scrub);
if ( pg2 > page )
@@ -500,13 +501,13 @@ int __init dom0_construct_pv(struct domain *d,
if ( page == NULL )
panic("Not enough RAM for domain 0 allocation\n");
alloc_spfn = mfn_x(page_to_mfn(page));
- alloc_epfn = alloc_spfn + d->tot_pages;
+ alloc_epfn = alloc_spfn + domain_tot_pages(d);
if ( initrd_len )
{
initrd_pfn = vinitrd_start ?
(vinitrd_start - v_start) >> PAGE_SHIFT :
- d->tot_pages;
+ domain_tot_pages(d);
initrd_mfn = mfn = initrd->mod_start;
count = PFN_UP(initrd_len);
if ( d->arch.physaddr_bitsize &&
@@ -541,9 +542,9 @@ int __init dom0_construct_pv(struct domain *d,
printk("PHYSICAL MEMORY ARRANGEMENT:\n"
" Dom0 alloc.: %"PRIpaddr"->%"PRIpaddr,
pfn_to_paddr(alloc_spfn), pfn_to_paddr(alloc_epfn));
- if ( d->tot_pages < nr_pages )
+ if ( domain_tot_pages(d) < nr_pages )
printk(" (%lu pages to be allocated)",
- nr_pages - d->tot_pages);
+ nr_pages - domain_tot_pages(d));
if ( initrd )
{
mpt_alloc = (paddr_t)initrd->mod_start << PAGE_SHIFT;
@@ -755,7 +756,7 @@ int __init dom0_construct_pv(struct domain *d,
snprintf(si->magic, sizeof(si->magic), "xen-3.0-x86_%d%s",
elf_64bit(&elf) ? 64 : 32, parms.pae ? "p" : "");
- count = d->tot_pages;
+ count = domain_tot_pages(d);
/* Set up the phys->machine table if not part of the initial mapping. */
if ( parms.p2m_base != UNSET_ADDR )
@@ -786,7 +787,7 @@ int __init dom0_construct_pv(struct domain *d,
process_pending_softirqs();
}
si->first_p2m_pfn = pfn;
- si->nr_p2m_frames = d->tot_pages - count;
+ si->nr_p2m_frames = domain_tot_pages(d) - count;
page_list_for_each ( page, &d->page_list )
{
mfn = mfn_x(page_to_mfn(page));
@@ -804,15 +805,15 @@ int __init dom0_construct_pv(struct domain *d,
process_pending_softirqs();
}
}
- BUG_ON(pfn != d->tot_pages);
+ BUG_ON(pfn != domain_tot_pages(d));
#ifndef NDEBUG
alloc_epfn += PFN_UP(initrd_len) + si->nr_p2m_frames;
#endif
while ( pfn < nr_pages )
{
- if ( (page = alloc_chunk(d, nr_pages - d->tot_pages)) == NULL )
+ if ( (page = alloc_chunk(d, nr_pages - domain_tot_pages(d))) == NULL )
panic("Not enough RAM for DOM0 reservation\n");
- while ( pfn < d->tot_pages )
+ while ( pfn < domain_tot_pages(d) )
{
mfn = mfn_x(page_to_mfn(page));
#ifndef NDEBUG
diff --git a/xen/arch/x86/pv/domain.c b/xen/arch/x86/pv/domain.c
index 4da0b2afff..c95652d1b8 100644
--- a/xen/arch/x86/pv/domain.c
+++ b/xen/arch/x86/pv/domain.c
@@ -173,7 +173,7 @@ int switch_compat(struct domain *d)
BUILD_BUG_ON(offsetof(struct shared_info, vcpu_info) != 0);
- if ( is_hvm_domain(d) || d->tot_pages != 0 )
+ if ( is_hvm_domain(d) || domain_tot_pages(d) != 0 )
return -EACCES;
if ( is_pv_32bit_domain(d) )
return 0;
diff --git a/xen/common/domctl.c b/xen/common/domctl.c
index 8b819f56e5..bdc24bbd7c 100644
--- a/xen/common/domctl.c
+++ b/xen/common/domctl.c
@@ -191,7 +191,7 @@ void getdomaininfo(struct domain *d, struct xen_domctl_getdomaininfo *info)
xsm_security_domaininfo(d, info);
- info->tot_pages = d->tot_pages;
+ info->tot_pages = domain_tot_pages(d);
info->max_pages = d->max_pages;
info->outstanding_pages = d->outstanding_pages;
info->shr_pages = atomic_read(&d->shr_pages);
diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c
index 5536d282b9..8bee6b3b66 100644
--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -2261,7 +2261,7 @@ gnttab_transfer(
* pages when it is dying.
*/
if ( unlikely(e->is_dying) ||
- unlikely(e->tot_pages >= e->max_pages) )
+ unlikely(domain_tot_pages(e) >= e->max_pages) )
{
spin_unlock(&e->page_alloc_lock);
@@ -2271,7 +2271,7 @@ gnttab_transfer(
else
gdprintk(XENLOG_INFO,
"Transferee d%d has no headroom (tot %u, max %u)\n",
- e->domain_id, e->tot_pages, e->max_pages);
+ e->domain_id, domain_tot_pages(e), e->max_pages);
gop.status = GNTST_general_error;
goto unlock_and_copyback;
diff --git a/xen/common/keyhandler.c b/xen/common/keyhandler.c
index f50490d0f3..87bd145374 100644
--- a/xen/common/keyhandler.c
+++ b/xen/common/keyhandler.c
@@ -271,7 +271,7 @@ static void dump_domains(unsigned char key)
atomic_read(&d->pause_count));
printk(" nr_pages=%d xenheap_pages=%d shared_pages=%u paged_pages=%u "
"dirty_cpus={%*pbl} max_pages=%u\n",
- d->tot_pages, d->xenheap_pages, atomic_read(&d->shr_pages),
+ domain_tot_pages(d), d->xenheap_pages, atomic_read(&d->shr_pages),
atomic_read(&d->paged_pages), CPUMASK_PR(d->dirty_cpumask),
d->max_pages);
printk(" handle=%02x%02x%02x%02x-%02x%02x-%02x%02x-"
diff --git a/xen/common/memory.c b/xen/common/memory.c
index c7d2bac452..bf464e8799 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -717,7 +717,7 @@ static long memory_exchange(XEN_GUEST_HANDLE_PARAM(xen_memory_exchange_t) arg)
/*
* Pages in in_chunk_list is stolen without
- * decreasing the tot_pages. If the domain is dying when
+ * decreasing domain_tot_pages(). If the domain is dying when
* assign pages, we need decrease the count. For those pages
* that has been assigned, it should be covered by
* domain_relinquish_resources().
@@ -1267,7 +1267,7 @@ long do_memory_op(unsigned long cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
switch ( op )
{
case XENMEM_current_reservation:
- rc = d->tot_pages;
+ rc = domain_tot_pages(d);
break;
case XENMEM_maximum_reservation:
rc = d->max_pages;
diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index 919a270587..bbd3163909 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -518,8 +518,8 @@ int domain_set_outstanding_pages(struct domain *d, unsigned long pages)
goto out;
}
- /* disallow a claim not exceeding current tot_pages or above max_pages */
- if ( (pages <= d->tot_pages) || (pages > d->max_pages) )
+ /* disallow a claim not exceeding domain_tot_pages() or above max_pages */
+ if ( (pages <= domain_tot_pages(d)) || (pages > d->max_pages) )
{
ret = -EINVAL;
goto out;
@@ -532,9 +532,9 @@ int domain_set_outstanding_pages(struct domain *d, unsigned long pages)
/*
* Note, if domain has already allocated memory before making a claim
- * then the claim must take tot_pages into account
+ * then the claim must take domain_tot_pages() into account
*/
- claim = pages - d->tot_pages;
+ claim = pages - domain_tot_pages(d);
if ( claim > avail_pages )
goto out;
@@ -2269,11 +2269,12 @@ int assign_pages(
if ( !(memflags & MEMF_no_refcount) )
{
- if ( unlikely((d->tot_pages + (1 << order)) > d->max_pages) )
+ unsigned int tot_pages = domain_tot_pages(d) + (1 << order);
+
+ if ( unlikely(tot_pages > d->max_pages) )
{
gprintk(XENLOG_INFO, "Over-allocation for domain %u: "
- "%u > %u\n", d->domain_id,
- d->tot_pages + (1 << order), d->max_pages);
+ "%u > %u\n", d->domain_id, tot_pages, d->max_pages);
rc = -E2BIG;
goto out;
}
diff --git a/xen/include/public/memory.h b/xen/include/public/memory.h
index cfdda6e2a8..126d0ff06e 100644
--- a/xen/include/public/memory.h
+++ b/xen/include/public/memory.h
@@ -553,8 +553,8 @@ DEFINE_XEN_GUEST_HANDLE(xen_mem_sharing_op_t);
*
* Note that a valid claim may be staked even after memory has been
* allocated for a domain. In this case, the claim is not incremental,
- * i.e. if the domain's tot_pages is 3, and a claim is staked for 10,
- * only 7 additional pages are claimed.
+ * i.e. if the domain's total page count is 3, and a claim is staked
+ * for 10, only 7 additional pages are claimed.
*
* Caller must be privileged or the hypercall fails.
*/
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 7c5c437247..1b6d7b941f 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -364,12 +364,18 @@ struct domain
spinlock_t page_alloc_lock; /* protects all the following fields */
struct page_list_head page_list; /* linked list */
struct page_list_head xenpage_list; /* linked list (size xenheap_pages) */
- unsigned int tot_pages; /* number of pages currently possesed */
- unsigned int xenheap_pages; /* # pages allocated from Xen heap */
- unsigned int outstanding_pages; /* pages claimed but not possessed */
- unsigned int max_pages; /* maximum value for tot_pages */
- atomic_t shr_pages; /* number of shared pages */
- atomic_t paged_pages; /* number of paged-out pages */
+
+ /*
+ * This field should only be directly accessed by domain_adjust_tot_pages()
+ * and the domain_tot_pages() helper function defined below.
+ */
+ unsigned int tot_pages;
+
+ unsigned int xenheap_pages; /* pages allocated from Xen heap */
+ unsigned int outstanding_pages; /* pages claimed but not possessed */
+ unsigned int max_pages; /* maximum value for domain_tot_pages() */
+ atomic_t shr_pages; /* shared pages */
+ atomic_t paged_pages; /* paged-out pages */
/* Scheduling. */
void *sched_priv; /* scheduler-specific data */
@@ -539,6 +545,12 @@ struct domain
#endif
};
+/* Return number of pages currently posessed by the domain */
+static inline unsigned int domain_tot_pages(const struct domain *d)
+{
+ return d->tot_pages;
+}
+
/* Protect updates/reads (resp.) of domain_list and domain_hash. */
extern spinlock_t domlist_update_lock;
extern rcu_read_lock_t domlist_read_lock;
--
2.20.1
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^ permalink raw reply related [flat|nested] 15+ messages in thread* [Xen-devel] [PATCH v8 3/4] mm: make pages allocated with MEMF_no_refcount safe to assign
2020-01-30 14:57 [Xen-devel] [PATCH v8 0/4] purge free_shared_domheap_page() Paul Durrant
2020-01-30 14:57 ` [Xen-devel] [PATCH v8 1/4] x86 / vmx: move teardown from domain_destroy() Paul Durrant
2020-01-30 14:57 ` [Xen-devel] [PATCH v8 2/4] add a domain_tot_pages() helper function Paul Durrant
@ 2020-01-30 14:57 ` Paul Durrant
2020-01-30 16:27 ` Jan Beulich
2020-01-30 14:57 ` [Xen-devel] [PATCH v8 4/4] x86 / vmx: use a MEMF_no_refcount domheap page for APIC_DEFAULT_PHYS_BASE Paul Durrant
3 siblings, 1 reply; 15+ messages in thread
From: Paul Durrant @ 2020-01-30 14:57 UTC (permalink / raw)
To: xen-devel
Cc: Stefano Stabellini, Julien Grall, Wei Liu, Konrad Rzeszutek Wilk,
George Dunlap, Andrew Cooper, Paul Durrant, Ian Jackson,
Volodymyr Babchuk, Roger Pau Monné
Currently it is unsafe to assign a domheap page allocated with
MEMF_no_refcount to a domain because the domain't 'tot_pages' will not
be incremented, but will be decrement when the page is freed (since
free_domheap_pages() has no way of telling that the increment was skipped).
This patch allocates a new 'count_info' bit for a PGC_extra flag
which is then used to mark pages when alloc_domheap_pages() is called
with MEMF_no_refcount. assign_pages() because it still needs to call
domain_adjust_tot_pages() to make sure the domain is appropriately
referenced. Hence it is modified to do that for PGC_extra pages even if it
is passed MEMF_no_refount.
The number of PGC_extra pages assigned to a domain is tracked in a new
'extra_pages' counter, which is then subtracted from 'total_pages' in
the domain_tot_pages() helper. Thus 'normal' page assignments will still
be appropriately checked against 'max_pages'.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
---
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: George Dunlap <George.Dunlap@eu.citrix.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Julien Grall <julien@xen.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Wei Liu <wl@xen.org>
Cc: Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
Cc: "Roger Pau Monné" <roger.pau@citrix.com>
v8:
- Drop the idea of post-allocation assignment adding an error path to
steal_page() if it encounters a PGC_extra page
- Tighten up the ASSERTs in assign_pages()
v7:
- s/PGC_no_refcount/PGC_extra/g
- Re-work allocation to account for 'extra' pages, also making it
safe to assign PGC_extra pages post-allocation
v6:
- Add an extra ASSERT into assign_pages() that PGC_no_refcount is not
set if MEMF_no_refcount is clear
- ASSERT that count_info is 0 in alloc_domheap_pages() and set to
PGC_no_refcount rather than ORing
v5:
- Make sure PGC_no_refcount is set before assign_pages() is called
- Don't bother to clear PGC_no_refcount in free_domheap_pages() and
drop ASSERT in free_heap_pages()
- Don't latch count_info in free_heap_pages()
v4:
- New in v4
---
xen/arch/x86/mm.c | 3 +-
xen/common/page_alloc.c | 63 +++++++++++++++++++++++++++++++---------
xen/include/asm-arm/mm.h | 5 +++-
xen/include/asm-x86/mm.h | 7 +++--
xen/include/xen/sched.h | 5 +++-
5 files changed, 64 insertions(+), 19 deletions(-)
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 8bb66cf30c..2796161c1f 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -4217,7 +4217,8 @@ int steal_page(
if ( !(owner = page_get_owner_and_reference(page)) )
goto fail;
- if ( owner != d || is_xen_heap_page(page) )
+ if ( owner != d || is_xen_heap_page(page) ||
+ (page->count_info & PGC_extra) )
goto fail_put;
/*
diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index bbd3163909..1ac9d9c719 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -2267,7 +2267,29 @@ int assign_pages(
goto out;
}
- if ( !(memflags & MEMF_no_refcount) )
+#ifndef NDEBUG
+ {
+ unsigned int extra_pages = 0;
+
+ for ( i = 0; i < (1ul << order); i++ )
+ {
+ ASSERT(!(pg[i].count_info & ~PGC_extra));
+ if ( pg[i].count_info & PGC_extra )
+ extra_pages++;
+ }
+
+ ASSERT(!extra_pages ||
+ ((memflags & MEMF_no_refcount) &&
+ extra_pages == 1u << order));
+ }
+#endif
+
+ if ( pg[0].count_info & PGC_extra )
+ {
+ d->extra_pages += 1u << order;
+ memflags &= ~MEMF_no_refcount;
+ }
+ else if ( !(memflags & MEMF_no_refcount) )
{
unsigned int tot_pages = domain_tot_pages(d) + (1 << order);
@@ -2278,18 +2300,19 @@ int assign_pages(
rc = -E2BIG;
goto out;
}
+ }
- if ( unlikely(domain_adjust_tot_pages(d, 1 << order) == (1 << order)) )
+ if ( !(memflags & MEMF_no_refcount) &&
+ unlikely(domain_adjust_tot_pages(d, 1 << order) == (1 << order)) )
get_knownalive_domain(d);
- }
for ( i = 0; i < (1 << order); i++ )
{
ASSERT(page_get_owner(&pg[i]) == NULL);
- ASSERT(!pg[i].count_info);
page_set_owner(&pg[i], d);
smp_wmb(); /* Domain pointer must be visible before updating refcnt. */
- pg[i].count_info = PGC_allocated | 1;
+ pg[i].count_info =
+ (pg[i].count_info & PGC_extra) | PGC_allocated | 1;
page_list_add_tail(&pg[i], &d->page_list);
}
@@ -2315,11 +2338,6 @@ struct page_info *alloc_domheap_pages(
if ( memflags & MEMF_no_owner )
memflags |= MEMF_no_refcount;
- else if ( (memflags & MEMF_no_refcount) && d )
- {
- ASSERT(!(memflags & MEMF_no_refcount));
- return NULL;
- }
if ( !dma_bitsize )
memflags &= ~MEMF_no_dma;
@@ -2332,11 +2350,23 @@ struct page_info *alloc_domheap_pages(
memflags, d)) == NULL)) )
return NULL;
- if ( d && !(memflags & MEMF_no_owner) &&
- assign_pages(d, pg, order, memflags) )
+ if ( d && !(memflags & MEMF_no_owner) )
{
- free_heap_pages(pg, order, memflags & MEMF_no_scrub);
- return NULL;
+ if ( memflags & MEMF_no_refcount )
+ {
+ unsigned long i;
+
+ for ( i = 0; i < (1ul << order); i++ )
+ {
+ ASSERT(!pg[i].count_info);
+ pg[i].count_info = PGC_extra;
+ }
+ }
+ if ( assign_pages(d, pg, order, memflags) )
+ {
+ free_heap_pages(pg, order, memflags & MEMF_no_scrub);
+ return NULL;
+ }
}
return pg;
@@ -2384,6 +2414,11 @@ void free_domheap_pages(struct page_info *pg, unsigned int order)
BUG();
}
arch_free_heap_page(d, &pg[i]);
+ if ( pg[i].count_info & PGC_extra )
+ {
+ ASSERT(d->extra_pages);
+ d->extra_pages--;
+ }
}
drop_dom_ref = !domain_adjust_tot_pages(d, -(1 << order));
diff --git a/xen/include/asm-arm/mm.h b/xen/include/asm-arm/mm.h
index 333efd3a60..7df91280bc 100644
--- a/xen/include/asm-arm/mm.h
+++ b/xen/include/asm-arm/mm.h
@@ -119,9 +119,12 @@ struct page_info
#define PGC_state_offlined PG_mask(2, 9)
#define PGC_state_free PG_mask(3, 9)
#define page_state_is(pg, st) (((pg)->count_info&PGC_state) == PGC_state_##st)
+/* Page is not reference counted */
+#define _PGC_extra PG_shift(10)
+#define PGC_extra PG_mask(1, 10)
/* Count of references to this frame. */
-#define PGC_count_width PG_shift(9)
+#define PGC_count_width PG_shift(10)
#define PGC_count_mask ((1UL<<PGC_count_width)-1)
/*
diff --git a/xen/include/asm-x86/mm.h b/xen/include/asm-x86/mm.h
index 2ca8882ad0..06d64d494d 100644
--- a/xen/include/asm-x86/mm.h
+++ b/xen/include/asm-x86/mm.h
@@ -77,9 +77,12 @@
#define PGC_state_offlined PG_mask(2, 9)
#define PGC_state_free PG_mask(3, 9)
#define page_state_is(pg, st) (((pg)->count_info&PGC_state) == PGC_state_##st)
+/* Page is not reference counted */
+#define _PGC_extra PG_shift(10)
+#define PGC_extra PG_mask(1, 10)
- /* Count of references to this frame. */
-#define PGC_count_width PG_shift(9)
+/* Count of references to this frame. */
+#define PGC_count_width PG_shift(10)
#define PGC_count_mask ((1UL<<PGC_count_width)-1)
/*
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 1b6d7b941f..21b5f4cebd 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -374,6 +374,7 @@ struct domain
unsigned int xenheap_pages; /* pages allocated from Xen heap */
unsigned int outstanding_pages; /* pages claimed but not possessed */
unsigned int max_pages; /* maximum value for domain_tot_pages() */
+ unsigned int extra_pages; /* pages not included in domain_tot_pages() */
atomic_t shr_pages; /* shared pages */
atomic_t paged_pages; /* paged-out pages */
@@ -548,7 +549,9 @@ struct domain
/* Return number of pages currently posessed by the domain */
static inline unsigned int domain_tot_pages(const struct domain *d)
{
- return d->tot_pages;
+ ASSERT(d->extra_pages <= d->tot_pages);
+
+ return d->tot_pages - d->extra_pages;
}
/* Protect updates/reads (resp.) of domain_list and domain_hash. */
--
2.20.1
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https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply related [flat|nested] 15+ messages in thread* [Xen-devel] [PATCH v8 4/4] x86 / vmx: use a MEMF_no_refcount domheap page for APIC_DEFAULT_PHYS_BASE
2020-01-30 14:57 [Xen-devel] [PATCH v8 0/4] purge free_shared_domheap_page() Paul Durrant
` (2 preceding siblings ...)
2020-01-30 14:57 ` [Xen-devel] [PATCH v8 3/4] mm: make pages allocated with MEMF_no_refcount safe to assign Paul Durrant
@ 2020-01-30 14:57 ` Paul Durrant
2020-02-03 8:10 ` Tian, Kevin
3 siblings, 1 reply; 15+ messages in thread
From: Paul Durrant @ 2020-01-30 14:57 UTC (permalink / raw)
To: xen-devel
Cc: Kevin Tian, Wei Liu, Andrew Cooper, Paul Durrant, Jun Nakajima,
Roger Pau Monné
vmx_alloc_vlapic_mapping() currently contains some very odd looking code
that allocates a MEMF_no_owner domheap page and then shares with the guest
as if it were a xenheap page. This then requires vmx_free_vlapic_mapping()
to call a special function in the mm code: free_shared_domheap_page().
By using a MEMF_no_refcount domheap page instead, the odd looking code in
vmx_alloc_vlapic_mapping() can simply use get_page_and_type() to set up a
writable mapping before insertion in the P2M and vmx_free_vlapic_mapping()
can simply release the page using put_page_alloc_ref() followed by
put_page_and_type(). This then allows free_shared_domheap_page() to be
purged.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
---
Cc: Jun Nakajima <jun.nakajima@intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Wei Liu <wl@xen.org>
Cc: "Roger Pau Monné" <roger.pau@citrix.com>
v4:
- Use a MEMF_no_refcount page rather than a 'normal' page
v2:
- Set an initial value for max_pages rather than avoiding the check in
assign_pages()
- Make domain_destroy() optional
---
xen/arch/x86/hvm/vmx/vmx.c | 21 ++++++++++++++++++---
xen/arch/x86/mm.c | 10 ----------
xen/include/asm-x86/mm.h | 2 --
3 files changed, 18 insertions(+), 15 deletions(-)
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 606f3dc2eb..7423d2421b 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -3028,12 +3028,22 @@ static int vmx_alloc_vlapic_mapping(struct domain *d)
if ( !cpu_has_vmx_virtualize_apic_accesses )
return 0;
- pg = alloc_domheap_page(d, MEMF_no_owner);
+ pg = alloc_domheap_page(d, MEMF_no_refcount);
if ( !pg )
return -ENOMEM;
+
+ if ( !get_page_and_type(pg, d, PGT_writable_page) )
+ {
+ /*
+ * The domain can't possibly know about this page yet, so failure
+ * here is a clear indication of something fishy going on.
+ */
+ domain_crash(d);
+ return -ENODATA;
+ }
+
mfn = page_to_mfn(pg);
clear_domain_page(mfn);
- share_xen_page_with_guest(pg, d, SHARE_rw);
d->arch.hvm.vmx.apic_access_mfn = mfn;
return set_mmio_p2m_entry(d, paddr_to_pfn(APIC_DEFAULT_PHYS_BASE), mfn,
@@ -3047,7 +3057,12 @@ static void vmx_free_vlapic_mapping(struct domain *d)
d->arch.hvm.vmx.apic_access_mfn = _mfn(0);
if ( !mfn_eq(mfn, _mfn(0)) )
- free_shared_domheap_page(mfn_to_page(mfn));
+ {
+ struct page_info *pg = mfn_to_page(mfn);
+
+ put_page_alloc_ref(pg);
+ put_page_and_type(pg);
+ }
}
static void vmx_install_vlapic_mapping(struct vcpu *v)
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 2796161c1f..461eed839d 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -496,16 +496,6 @@ void share_xen_page_with_guest(struct page_info *page, struct domain *d,
spin_unlock(&d->page_alloc_lock);
}
-void free_shared_domheap_page(struct page_info *page)
-{
- put_page_alloc_ref(page);
- if ( !test_and_clear_bit(_PGC_xen_heap, &page->count_info) )
- ASSERT_UNREACHABLE();
- page->u.inuse.type_info = 0;
- page_set_owner(page, NULL);
- free_domheap_page(page);
-}
-
void make_cr3(struct vcpu *v, mfn_t mfn)
{
struct domain *d = v->domain;
diff --git a/xen/include/asm-x86/mm.h b/xen/include/asm-x86/mm.h
index 06d64d494d..fafb3af46d 100644
--- a/xen/include/asm-x86/mm.h
+++ b/xen/include/asm-x86/mm.h
@@ -320,8 +320,6 @@ struct page_info
#define maddr_get_owner(ma) (page_get_owner(maddr_to_page((ma))))
-extern void free_shared_domheap_page(struct page_info *page);
-
#define frame_table ((struct page_info *)FRAMETABLE_VIRT_START)
extern unsigned long max_page;
extern unsigned long total_pages;
--
2.20.1
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^ permalink raw reply related [flat|nested] 15+ messages in thread