|
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen-unstable] x86/mm: Ensure maps used by nested hvm code cannot be paged out
# HG changeset patch
# User Andres Lagar-Cavilla <andres@xxxxxxxxxxxxxxxx>
# Date 1322760084 0
# Node ID f71ecec8be2e6bfd3ad9543395194514ef8c8bd9
# Parent 3075955bbea4bf9430a3b800ff157e99ad2d8fd0
x86/mm: Ensure maps used by nested hvm code cannot be paged out
The nested hvm code maps pages of the guest hvm. These maps live beyond
a hypervisor entry/exit pair, and thus their liveness cannot be ensured
with get_gfn/put_gfn critical sections. Ensure their liveness by
increasing the page ref count, instead.
Signed-off-by: Andres Lagar-Cavilla <andres@xxxxxxxxxxxxxxxx>
Acked-by: Tim Deegan <tim@xxxxxxx>
Committed-by: Tim Deegan <tim@xxxxxxx>
---
diff -r 3075955bbea4 -r f71ecec8be2e xen/arch/x86/hvm/hvm.c
--- a/xen/arch/x86/hvm/hvm.c Thu Dec 01 17:21:24 2011 +0000
+++ b/xen/arch/x86/hvm/hvm.c Thu Dec 01 17:21:24 2011 +0000
@@ -1823,12 +1823,16 @@
return 0;
}
-/* We leave this function holding a lock on the p2m entry */
+/* On non-NULL return, we leave this function holding an additional
+ * ref on the underlying mfn, if any */
static void *__hvm_map_guest_frame(unsigned long gfn, bool_t writable)
{
+ void *map;
unsigned long mfn;
p2m_type_t p2mt;
+ struct page_info *pg;
struct domain *d = current->domain;
+ int rc;
mfn = mfn_x(writable
? get_gfn_unshare(d, gfn, &p2mt)
@@ -1850,7 +1854,21 @@
if ( writable )
paging_mark_dirty(d, mfn);
- return map_domain_page(mfn);
+ /* Get a ref on the page, considering that it could be shared */
+ pg = mfn_to_page(mfn);
+ rc = get_page(pg, d);
+ if ( !rc && !writable )
+ /* Page could be shared */
+ rc = get_page(pg, dom_cow);
+ if ( !rc )
+ {
+ put_gfn(d, gfn);
+ return NULL;
+ }
+
+ map = map_domain_page(mfn);
+ put_gfn(d, gfn);
+ return map;
}
void *hvm_map_guest_frame_rw(unsigned long gfn)
@@ -1866,11 +1884,16 @@
void hvm_unmap_guest_frame(void *p)
{
if ( p )
+ {
+ unsigned long mfn = domain_page_map_to_mfn(p);
unmap_domain_page(p);
+ put_page(mfn_to_page(mfn));
+ }
}
-static void *hvm_map_entry(unsigned long va, unsigned long *gfn)
+static void *hvm_map_entry(unsigned long va)
{
+ unsigned long gfn;
uint32_t pfec;
char *v;
@@ -1887,11 +1910,11 @@
* treat it as a kernel-mode read (i.e. no access checks).
*/
pfec = PFEC_page_present;
- *gfn = paging_gva_to_gfn(current, va, &pfec);
+ gfn = paging_gva_to_gfn(current, va, &pfec);
if ( (pfec == PFEC_page_paged) || (pfec == PFEC_page_shared) )
goto fail;
- v = hvm_map_guest_frame_rw(*gfn);
+ v = hvm_map_guest_frame_rw(gfn);
if ( v == NULL )
goto fail;
@@ -1902,11 +1925,9 @@
return NULL;
}
-static void hvm_unmap_entry(void *p, unsigned long gfn)
+static void hvm_unmap_entry(void *p)
{
hvm_unmap_guest_frame(p);
- if ( p && (gfn != INVALID_GFN) )
- put_gfn(current->domain, gfn);
}
static int hvm_load_segment_selector(
@@ -1918,7 +1939,6 @@
int fault_type = TRAP_invalid_tss;
struct cpu_user_regs *regs = guest_cpu_user_regs();
struct vcpu *v = current;
- unsigned long pdesc_gfn = INVALID_GFN;
if ( regs->eflags & X86_EFLAGS_VM )
{
@@ -1952,7 +1972,7 @@
if ( ((sel & 0xfff8) + 7) > desctab.limit )
goto fail;
- pdesc = hvm_map_entry(desctab.base + (sel & 0xfff8), &pdesc_gfn);
+ pdesc = hvm_map_entry(desctab.base + (sel & 0xfff8));
if ( pdesc == NULL )
goto hvm_map_fail;
@@ -2012,7 +2032,7 @@
desc.b |= 0x100;
skip_accessed_flag:
- hvm_unmap_entry(pdesc, pdesc_gfn);
+ hvm_unmap_entry(pdesc);
segr.base = (((desc.b << 0) & 0xff000000u) |
((desc.b << 16) & 0x00ff0000u) |
@@ -2028,7 +2048,7 @@
return 0;
unmap_and_fail:
- hvm_unmap_entry(pdesc, pdesc_gfn);
+ hvm_unmap_entry(pdesc);
fail:
hvm_inject_exception(fault_type, sel & 0xfffc, 0);
hvm_map_fail:
@@ -2043,7 +2063,7 @@
struct cpu_user_regs *regs = guest_cpu_user_regs();
struct segment_register gdt, tr, prev_tr, segr;
struct desc_struct *optss_desc = NULL, *nptss_desc = NULL, tss_desc;
- unsigned long eflags, optss_gfn = INVALID_GFN, nptss_gfn = INVALID_GFN;
+ unsigned long eflags;
int exn_raised, rc;
struct {
u16 back_link,__blh;
@@ -2069,11 +2089,11 @@
goto out;
}
- optss_desc = hvm_map_entry(gdt.base + (prev_tr.sel & 0xfff8), &optss_gfn);
+ optss_desc = hvm_map_entry(gdt.base + (prev_tr.sel & 0xfff8));
if ( optss_desc == NULL )
goto out;
- nptss_desc = hvm_map_entry(gdt.base + (tss_sel & 0xfff8), &nptss_gfn);
+ nptss_desc = hvm_map_entry(gdt.base + (tss_sel & 0xfff8));
if ( nptss_desc == NULL )
goto out;
@@ -2238,8 +2258,8 @@
}
out:
- hvm_unmap_entry(optss_desc, optss_gfn);
- hvm_unmap_entry(nptss_desc, nptss_gfn);
+ hvm_unmap_entry(optss_desc);
+ hvm_unmap_entry(nptss_desc);
}
#define HVMCOPY_from_guest (0u<<0)
diff -r 3075955bbea4 -r f71ecec8be2e xen/arch/x86/hvm/svm/nestedsvm.c
--- a/xen/arch/x86/hvm/svm/nestedsvm.c Thu Dec 01 17:21:24 2011 +0000
+++ b/xen/arch/x86/hvm/svm/nestedsvm.c Thu Dec 01 17:21:24 2011 +0000
@@ -81,10 +81,6 @@
if (nv->nv_vvmcx == NULL)
return 0;
nv->nv_vvmcxaddr = vmcbaddr;
- /* put_gfn here even though the map survives beyond this caller.
- * The map can likely survive beyond a hypervisor exit, thus we
- * need to put the gfn */
- put_gfn(current->domain, vmcbaddr >> PAGE_SHIFT);
}
return 1;
@@ -358,7 +354,6 @@
ioport_80 = test_bit(0x80, ns_viomap);
ioport_ed = test_bit(0xed, ns_viomap);
hvm_unmap_guest_frame(ns_viomap);
- put_gfn(current->domain, svm->ns_iomap_pa >> PAGE_SHIFT);
svm->ns_iomap = nestedhvm_vcpu_iomap_get(ioport_80, ioport_ed);
@@ -889,7 +884,6 @@
enabled = test_bit(port, io_bitmap);
hvm_unmap_guest_frame(io_bitmap);
- put_gfn(current->domain, gfn);
if (!enabled)
return NESTEDHVM_VMEXIT_HOST;
diff -r 3075955bbea4 -r f71ecec8be2e xen/arch/x86/hvm/vmx/vvmx.c
--- a/xen/arch/x86/hvm/vmx/vvmx.c Thu Dec 01 17:21:24 2011 +0000
+++ b/xen/arch/x86/hvm/vmx/vvmx.c Thu Dec 01 17:21:24 2011 +0000
@@ -560,10 +560,7 @@
if (nvmx->iobitmap[index])
hvm_unmap_guest_frame (nvmx->iobitmap[index]);
gpa = __get_vvmcs(vcpu_nestedhvm(v).nv_vvmcx, vmcs_reg);
- nvmx->iobitmap[index] = hvm_map_guest_frame_ro (gpa >> PAGE_SHIFT);
- /* See comment in nestedsvm_vmcb_map re putting this gfn and
- * liveness of the map it backs */
- put_gfn(current->domain, gpa >> PAGE_SHIFT);
+ nvmx->iobitmap[index] = hvm_map_guest_frame_ro(gpa >> PAGE_SHIFT);
}
static inline void map_io_bitmap_all(struct vcpu *v)
@@ -1138,12 +1135,9 @@
if ( nvcpu->nv_vvmcxaddr == VMCX_EADDR )
{
- nvcpu->nv_vvmcx = hvm_map_guest_frame_rw (gpa >> PAGE_SHIFT);
+ nvcpu->nv_vvmcx = hvm_map_guest_frame_rw(gpa >> PAGE_SHIFT);
nvcpu->nv_vvmcxaddr = gpa;
map_io_bitmap_all (v);
- /* See comment in nestedsvm_vmcb_map regarding putting this
- * gfn and liveness of the map that uses it */
- put_gfn(current->domain, gpa >> PAGE_SHIFT);
}
vmreturn(regs, VMSUCCEED);
@@ -1205,7 +1199,6 @@
if ( vvmcs )
__set_vvmcs(vvmcs, NVMX_LAUNCH_STATE, 0);
hvm_unmap_guest_frame(vvmcs);
- put_gfn(current->domain, gpa >> PAGE_SHIFT);
}
vmreturn(regs, VMSUCCEED);
_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-changelog
|
 |
Lists.xenproject.org is hosted with RackSpace, monitoring our |