From: Paul Durrant <pdurrant@amazon.com>
To: <xen-devel@lists.xenproject.org>
Cc: "Kevin Tian" <kevin.tian@intel.com>,
"Stefano Stabellini" <sstabellini@kernel.org>,
"Julien Grall" <julien@xen.org>,
"Jun Nakajima" <jun.nakajima@intel.com>, "Wei Liu" <wl@xen.org>,
"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
"George Dunlap" <George.Dunlap@eu.citrix.com>,
"Andrew Cooper" <andrew.cooper3@citrix.com>,
"Paul Durrant" <pdurrant@amazon.com>,
"Ian Jackson" <ian.jackson@eu.citrix.com>,
"Roger Pau Monné" <roger.pau@citrix.com>
Subject: [Xen-devel] [PATCH 3/3] x86 / vmx: use a 'normal' domheap page for APIC_DEFAULT_PHYS_BASE
Date: Tue, 21 Jan 2020 12:00:09 +0000 [thread overview]
Message-ID: <20200121120009.1767-4-pdurrant@amazon.com> (raw)
In-Reply-To: <20200121120009.1767-1-pdurrant@amazon.com>
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 'normal' domheap page (i.e. by not passing MEMF_no_owner to
alloc_domheap_page()), 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.
There is, however, some fall-out from this simplification:
- alloc_domheap_page() will now call assign_pages() and run into the fact
that 'max_pages' is not set until some time after domain_create(). To
avoid an allocation failure, assign_pages() is modified to ignore the
max_pages limit if 'creation_finished' is false. That value is not set
to true until domain_unpause_by_systemcontroller() is called, and thus
the guest cannot run (and hence cause memory allocation) until
creation_finished is set to true.
- Because the domheap page is no longer a pseudo-xenheap page, the
reference counting will prevent the domain from being destroyed. Thus
the call to vmx_free_vlapic_mapping() is moved from the
domain_destroy() method into the domain_relinquish_resources() method.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
---
Cc: Jun Nakajima <jun.nakajima@intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>
Cc: Jan Beulich <jbeulich@suse.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>
---
xen/arch/x86/hvm/vmx/vmx.c | 29 ++++++++++++++++++++++-------
xen/arch/x86/mm.c | 10 ----------
xen/common/page_alloc.c | 3 ++-
xen/include/asm-x86/mm.h | 2 --
4 files changed, 24 insertions(+), 20 deletions(-)
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 3fd3ac61e1..a2e6081485 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -421,10 +421,6 @@ static int vmx_domain_initialise(struct domain *d)
}
static void vmx_domain_relinquish_resources(struct domain *d)
-{
-}
-
-static void vmx_domain_destroy(struct domain *d)
{
if ( !has_vlapic(d) )
return;
@@ -432,6 +428,10 @@ static void vmx_domain_destroy(struct domain *d)
vmx_free_vlapic_mapping(d);
}
+static void vmx_domain_destroy(struct domain *d)
+{
+}
+
static int vmx_vcpu_initialise(struct vcpu *v)
{
int rc;
@@ -3034,12 +3034,22 @@ 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, 0);
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,
@@ -3052,7 +3062,12 @@ static void vmx_free_vlapic_mapping(struct domain *d)
mfn_t mfn = d->arch.hvm.vmx.apic_access_mfn;
if ( !mfn_eq(mfn, INVALID_MFN) )
- 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 654190e9e9..2a6d2e8af9 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/common/page_alloc.c b/xen/common/page_alloc.c
index 919a270587..ef327072ed 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -2269,7 +2269,8 @@ int assign_pages(
if ( !(memflags & MEMF_no_refcount) )
{
- if ( unlikely((d->tot_pages + (1 << order)) > d->max_pages) )
+ if ( unlikely((d->tot_pages + (1 << order)) > d->max_pages) &&
+ d->creation_finished )
{
gprintk(XENLOG_INFO, "Over-allocation for domain %u: "
"%u > %u\n", d->domain_id,
diff --git a/xen/include/asm-x86/mm.h b/xen/include/asm-x86/mm.h
index 2ca8882ad0..e429f38228 100644
--- a/xen/include/asm-x86/mm.h
+++ b/xen/include/asm-x86/mm.h
@@ -317,8 +317,6 @@ 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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next prev parent reply other threads:[~2020-01-21 12:01 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-21 12:00 [Xen-devel] [PATCH 0/3] purge free_shared_domheap_page() Paul Durrant
2020-01-21 12:00 ` [Xen-devel] [PATCH 1/3] x86 / vmx: make apic_access_mfn type-safe Paul Durrant
2020-01-22 2:51 ` Tian, Kevin
2020-01-22 14:05 ` Andrew Cooper
2020-01-22 15:48 ` Jan Beulich
2020-01-21 12:00 ` [Xen-devel] [PATCH 2/3] x86 / hvm: add domain_relinquish_resources() method Paul Durrant
2020-01-22 15:50 ` Jan Beulich
2020-01-22 15:56 ` Durrant, Paul
2020-01-22 16:00 ` Jan Beulich
2020-01-22 16:02 ` Durrant, Paul
2020-01-21 12:00 ` Paul Durrant [this message]
2020-01-21 12:29 ` [Xen-devel] [PATCH 3/3] x86 / vmx: use a 'normal' domheap page for APIC_DEFAULT_PHYS_BASE Julien Grall
2020-01-21 12:37 ` Durrant, Paul
2020-01-22 3:19 ` Tian, Kevin
2020-01-22 11:25 ` Durrant, Paul
2020-01-22 16:17 ` Jan Beulich
2020-01-22 16:27 ` Durrant, Paul
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