This isn't targeted at 4.1 given the freeze, but is instead just a RFC.
This is an attempt to properly fix the hypervisor crash previously
described in
http://marc.info/?l=xen-devel&m=128396289707362&w=2
In looking into this issue, I think the proper fix is to move the
xsm_mmu_* and xsm_update_va_mapping hook calls later in the callers,
after more validation has been performed and the page_info struct is
readily available, and pass the page_info to the hooks. This patch moves
the xsm_mmu_normal_update, xsm_mmu_machphys_update and
xsm_update_va_mapping hook calls accordingly, and updates their
interfaces and hook function implementations. This appears to resolve
the crashes for me. However, as I am not overly familiar with this area
of code, I'd appreciate any feedback or suggestions for improvement.
Thanks.
---
xen/arch/x86/mm.c | 30 ++++++++++++++++++------------
xen/include/xsm/xsm.h | 28 +++++++++++++++-------------
xen/xsm/dummy.c | 11 ++++++-----
xen/xsm/flask/hooks.c | 41 ++++++++---------------------------------
4 files changed, 47 insertions(+), 63 deletions(-)
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -3416,10 +3416,6 @@
{
p2m_type_t p2mt;
- rc = xsm_mmu_normal_update(d, pg_owner, req.val);
- if ( rc )
- break;
-
req.ptr -= cmd;
gmfn = req.ptr >> PAGE_SHIFT;
mfn = mfn_x(gfn_to_mfn(p2m_get_hostp2m(pt_owner), gmfn, &p2mt));
@@ -3445,6 +3441,13 @@
(unsigned long)(req.ptr & ~PAGE_MASK));
page = mfn_to_page(mfn);
+ rc = xsm_mmu_normal_update(d, req.val, page);
+ if ( rc ) {
+ unmap_domain_page_with_cache(va, &mapcache);
+ put_page(page);
+ break;
+ }
+
if ( page_lock(page) )
{
switch ( page->u.inuse.type_info & PGT_type_mask )
@@ -3612,10 +3615,6 @@
mfn = req.ptr >> PAGE_SHIFT;
gpfn = req.val;
- rc = xsm_mmu_machphys_update(d, mfn);
- if ( rc )
- break;
-
if ( unlikely(!get_page_from_pagenr(mfn, pg_owner)) )
{
MEM_LOG("Could not get page for mach->phys update");
@@ -3628,6 +3627,10 @@
break;
}
+ rc = xsm_mmu_machphys_update(d, mfn_to_page(mfn));
+ if ( rc )
+ break;
+
set_gpfn_from_mfn(mfn, gpfn);
okay = 1;
@@ -4247,10 +4250,6 @@
perfc_incr(calls_to_update_va);
- rc = xsm_update_va_mapping(d, pg_owner, val);
- if ( rc )
- return rc;
-
rc = -EINVAL;
pl1e = guest_map_l1e(v, va, &gl1mfn);
if ( unlikely(!pl1e || !get_page_from_pagenr(gl1mfn, d)) )
@@ -4270,6 +4269,13 @@
goto out;
}
+ rc = xsm_update_va_mapping(d, val, gl1pg);
+ if ( rc ) {
+ page_unlock(gl1pg);
+ put_page(gl1pg);
+ goto out;
+ }
+
rc = mod_l1_entry(pl1e, val, gl1mfn, 0, v, pg_owner) ? 0 : -EINVAL;
page_unlock(gl1pg);
diff --git a/xen/include/xsm/xsm.h b/xen/include/xsm/xsm.h
--- a/xen/include/xsm/xsm.h
+++ b/xen/include/xsm/xsm.h
@@ -136,11 +136,12 @@
int (*getidletime) (void);
int (*machine_memory_map) (void);
int (*domain_memory_map) (struct domain *d);
- int (*mmu_normal_update) (struct domain *d, struct domain *f,
- intpte_t fpte);
- int (*mmu_machphys_update) (struct domain *d, unsigned long mfn);
- int (*update_va_mapping) (struct domain *d, struct domain *f,
- l1_pgentry_t pte);
+ int (*mmu_normal_update) (struct domain *d,
+ intpte_t fpte, struct page_info *page);
+ int (*mmu_machphys_update) (struct domain *d, struct page_info *page);
+ int (*update_va_mapping) (struct domain *d,
+ l1_pgentry_t pte,
+ struct page_info *page);
int (*add_to_physmap) (struct domain *d1, struct domain *d2);
int (*sendtrigger) (struct domain *d);
int (*test_assign_device) (uint32_t machine_bdf);
@@ -567,21 +568,22 @@
return xsm_call(domain_memory_map(d));
}
-static inline int xsm_mmu_normal_update (struct domain *d, struct domain *f,
- intpte_t fpte)
+static inline int xsm_mmu_normal_update (struct domain *d,
+ intpte_t fpte, struct page_info *page)
{
- return xsm_call(mmu_normal_update(d, f, fpte));
+ return xsm_call(mmu_normal_update(d, fpte, page));
}
-static inline int xsm_mmu_machphys_update (struct domain *d, unsigned long mfn)
+static inline int xsm_mmu_machphys_update (struct domain *d, struct page_info
*page)
{
- return xsm_call(mmu_machphys_update(d, mfn));
+ return xsm_call(mmu_machphys_update(d, page));
}
-static inline int xsm_update_va_mapping(struct domain *d, struct domain *f,
- l1_pgentry_t pte)
+static inline int xsm_update_va_mapping(struct domain *d,
+ l1_pgentry_t pte,
+ struct page_info *page)
{
- return xsm_call(update_va_mapping(d, f, pte));
+ return xsm_call(update_va_mapping(d, pte, page));
}
static inline int xsm_add_to_physmap(struct domain *d1, struct domain *d2)
diff --git a/xen/xsm/dummy.c b/xen/xsm/dummy.c
--- a/xen/xsm/dummy.c
+++ b/xen/xsm/dummy.c
@@ -405,19 +405,20 @@
return 0;
}
-static int dummy_mmu_normal_update (struct domain *d, struct domain *f,
- intpte_t fpte)
+static int dummy_mmu_normal_update (struct domain *d,
+ intpte_t fpte, struct page_info *page)
{
return 0;
}
-static int dummy_mmu_machphys_update (struct domain *d, unsigned long mfn)
+static int dummy_mmu_machphys_update (struct domain *d, struct page_info *page)
{
return 0;
}
-static int dummy_update_va_mapping (struct domain *d, struct domain *f,
- l1_pgentry_t pte)
+static int dummy_update_va_mapping (struct domain *d,
+ l1_pgentry_t pte,
+ struct page_info *page)
{
return 0;
}
diff --git a/xen/xsm/flask/hooks.c b/xen/xsm/flask/hooks.c
--- a/xen/xsm/flask/hooks.c
+++ b/xen/xsm/flask/hooks.c
@@ -347,26 +347,6 @@
return rc;
}
-static int get_mfn_sid(unsigned long mfn, u32 *sid)
-{
- int rc = 0;
- struct page_info *page;
-
- if ( mfn_valid(mfn) )
- {
- /*mfn is valid if this is a page that Xen is tracking!*/
- page = mfn_to_page(mfn);
- rc = get_page_sid(page, sid);
- }
- else
- {
- /*Possibly an untracked IO page?*/
- rc = security_iomem_sid(mfn, sid);
- }
-
- return rc;
-}
-
static int flask_memory_adjust_reservation(struct domain *d1, struct domain
*d2)
{
return domain_has_perm(d1, d2, SECCLASS_MMU, MMU__ADJUST);
@@ -1006,12 +986,11 @@
return domain_has_perm(current->domain, d, SECCLASS_MMU, MMU__MEMORYMAP);
}
-static int flask_mmu_normal_update(struct domain *d, struct domain *f,
- intpte_t fpte)
+static int flask_mmu_normal_update(struct domain *d,
+ intpte_t fpte, struct page_info *page)
{
int rc = 0;
u32 map_perms = MMU__MAP_READ;
- unsigned long fmfn;
struct domain_security_struct *dsec;
u32 fsid;
@@ -1020,42 +999,38 @@
if ( l1e_get_flags(l1e_from_intpte(fpte)) & _PAGE_RW )
map_perms |= MMU__MAP_WRITE;
- fmfn = gmfn_to_mfn(f, l1e_get_pfn(l1e_from_intpte(fpte)));
-
- rc = get_mfn_sid(fmfn, &fsid);
+ rc = get_page_sid(page, &fsid);
if ( rc )
return rc;
return avc_has_perm(dsec->sid, fsid, SECCLASS_MMU, map_perms, NULL);
}
-static int flask_mmu_machphys_update(struct domain *d, unsigned long mfn)
+static int flask_mmu_machphys_update(struct domain *d, struct page_info *page)
{
int rc = 0;
u32 psid;
struct domain_security_struct *dsec;
dsec = d->ssid;
- rc = get_mfn_sid(mfn, &psid);
+ rc = get_page_sid(page, &psid);
if ( rc )
return rc;
return avc_has_perm(dsec->sid, psid, SECCLASS_MMU, MMU__UPDATEMP, NULL);
}
-static int flask_update_va_mapping(struct domain *d, struct domain *f,
- l1_pgentry_t pte)
+static int flask_update_va_mapping(struct domain *d,
+ l1_pgentry_t pte, struct page_info *page)
{
int rc = 0;
u32 psid;
u32 map_perms = MMU__MAP_READ;
- unsigned long mfn;
struct domain_security_struct *dsec;
dsec = d->ssid;
- mfn = gmfn_to_mfn(f, l1e_get_pfn(pte));
- rc = get_mfn_sid(mfn, &psid);
+ rc = get_page_sid(page, &psid);
if ( rc )
return rc;
--
Stephen Smalley
National Security Agency
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