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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH for-4.5 v10 14/19] xen/arm: Data abort exception (R/W) mem_events.
This patch enables to store, set, check and deliver LPAE R/W mem_events.
As the LPAE PTE's lack enough available software programmable bits,
we store the permissions in a Radix tree. A custom boolean, access_in_use,
specifies if the tree is in use to avoid unecessary lookups on an empty tree.
Signed-off-by: Tamas K Lengyel <tklengyel@xxxxxxxxxxxxx>
---
v10: - Remove ASSERT from MEMACCESS case.
- Flush the tlb in the MEMACCESS case as we progress.
- Typos and style fixes.
v8: - Revert to arch specific p2m_mem_access_check.
- Retire dabt_dfsc enum and use FSC_FLT defines.
- Revert to Radix tree approach and use access_in_use flag to
indicate if the tree is in use or not to avoid uneccessary lookups.
v7: - Removed p2m_shatter_page and p2m_set_permission into separate
patch.
- Replace Radix tree settings store with extended struct page_info
approach. This way the trap handlers can use the MMU directly to
locate the permission store instead of having to do a tree-lookup.
- Add p2m_get_entry/set_entry compat functions which are required by
the common mem_access_check function.
- Typo fixes.
v6: - Add helper function p2m_shatter_page.
- Only allocate 4k pages when mem_access is in use.
- If no setting was found in radix tree but PTE exists,
return rwx as permission.
- Move the inclusion of various headers into this patch.
- Make npfec a const.
v5: - Move p2m_set_entry's logic into apply_one_level via
a new p2m_op, MEMACCESS.
v4: - Add p2m_mem_access_radix_set function to be called
when inserting new PTE's and when updating existing entries.
- Switch p2m_mem_access_check to return bool_t.
- Use new struct npfec to pass violation info.
v3: - Add new function for updating the PTE entries, p2m_set_entry.
- Use the new struct npfec to pass violation information.
- Implement n2rwx, rx2rw and listener required routines.
v2: - Patch been split to ease the review process.
- Add definitions of data abort data fetch status codes (enum dabt_dfsc)
and only call p2m_mem_access_check for traps caused by permission
violations.
- Only call p2m_write_pte in p2m_lookup if the PTE permission actually
changed.
- Properly save settings in the Radix tree and pause the VCPU with
mem_event_vcpu_pause.
---
xen/arch/arm/p2m.c | 364 +++++++++++++++++++++++++++++++++++++++++++++-
xen/arch/arm/traps.c | 27 +++-
xen/include/asm-arm/p2m.h | 15 ++
3 files changed, 398 insertions(+), 8 deletions(-)
diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 1fb531d..ba57ac2 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -5,6 +5,9 @@
#include <xen/errno.h>
#include <xen/domain_page.h>
#include <xen/bitops.h>
+#include <xen/mem_event.h>
+#include <xen/mem_access.h>
+#include <public/mem_event.h>
#include <asm/flushtlb.h>
#include <asm/gic.h>
#include <asm/event.h>
@@ -414,12 +417,41 @@ static int p2m_create_table(struct domain *d, lpae_t
*entry,
return 0;
}
+static int p2m_mem_access_radix_set(struct p2m_domain *p2m, unsigned long pfn,
+ p2m_access_t a)
+{
+ int rc;
+
+ if ( a == p2m_access_rwx )
+ {
+ if ( p2m->access_in_use )
+ radix_tree_delete(&p2m->mem_access_settings, pfn);
+
+ return 0;
+ }
+
+ rc = radix_tree_insert(&p2m->mem_access_settings, pfn,
+ radix_tree_int_to_ptr(a));
+ if ( -EEXIST == rc )
+ {
+ /* If a setting existed already, change it to the new one */
+ radix_tree_replace_slot(
+ radix_tree_lookup_slot(
+ &p2m->mem_access_settings, pfn),
+ radix_tree_int_to_ptr(a));
+ rc = 0;
+ }
+
+ return rc;
+}
+
enum p2m_operation {
INSERT,
ALLOCATE,
REMOVE,
RELINQUISH,
CACHEFLUSH,
+ MEMACCESS,
};
/* Put any references on the single 4K page referenced by pte. TODO:
@@ -553,13 +585,22 @@ static int apply_one_level(struct domain *d,
if ( p2m_valid(orig_pte) )
return P2M_ONE_DESCEND;
- if ( is_mapping_aligned(*addr, end_gpaddr, 0, level_size) )
+ if ( is_mapping_aligned(*addr, end_gpaddr, 0, level_size) &&
+ /* We only create superpages when mem_access is not in use. */
+ (level == 3 || (level < 3 && !p2m->access_in_use)) )
{
struct page_info *page;
page = alloc_domheap_pages(d, level_shift - PAGE_SHIFT, 0);
if ( page )
{
+ rc = p2m_mem_access_radix_set(p2m, paddr_to_pfn(*addr), a);
+ if ( rc < 0 )
+ {
+ free_domheap_page(page);
+ return rc;
+ }
+
pte = mfn_to_p2m_entry(page_to_mfn(page), mattr, t, a);
if ( level < 3 )
pte.p2m.table = 0;
@@ -580,8 +621,8 @@ static int apply_one_level(struct domain *d,
/*
* If we get here then we failed to allocate a sufficiently
* large contiguous region for this level (which can't be
- * L3). Create a page table and continue to descend so we try
- * smaller allocations.
+ * L3) or mem_access is in use. Create a page table and
+ * continue to descend so we try smaller allocations.
*/
rc = p2m_create_table(d, entry, 0, flush_cache);
if ( rc < 0 )
@@ -591,9 +632,14 @@ static int apply_one_level(struct domain *d,
case INSERT:
if ( is_mapping_aligned(*addr, end_gpaddr, *maddr, level_size) &&
- /* We do not handle replacing an existing table with a superpage */
- (level == 3 || !p2m_table(orig_pte)) )
+ /* We do not handle replacing an existing table with a superpage
+ * or when mem_access is in use. */
+ (level == 3 || (!p2m_table(orig_pte) && !p2m->access_in_use)) )
{
+ rc = p2m_mem_access_radix_set(p2m, paddr_to_pfn(*addr), a);
+ if ( rc < 0 )
+ return rc;
+
/* New mapping is superpage aligned, make it */
pte = mfn_to_p2m_entry(*maddr >> PAGE_SHIFT, mattr, t, a);
if ( level < 3 )
@@ -709,6 +755,7 @@ static int apply_one_level(struct domain *d,
memset(&pte, 0x00, sizeof(pte));
p2m_write_pte(entry, pte, flush_cache);
+ p2m_mem_access_radix_set(p2m, paddr_to_pfn(*addr), p2m_access_rwx);
*addr += level_size;
*maddr += level_size;
@@ -753,6 +800,48 @@ static int apply_one_level(struct domain *d,
*addr += PAGE_SIZE;
return P2M_ONE_PROGRESS_NOP;
}
+
+ case MEMACCESS:
+ if ( level < 3 )
+ {
+ if ( !p2m_valid(orig_pte) )
+ {
+ *addr += level_size;
+ return P2M_ONE_PROGRESS_NOP;
+ }
+
+ /* Shatter large pages as we descend */
+ if ( p2m_mapping(orig_pte) )
+ {
+ rc = p2m_shatter_page(d, entry, level, flush_cache);
+
+ if ( rc < 0 )
+ return rc;
+ } /* else: an existing table mapping -> descend */
+
+ return P2M_ONE_DESCEND;
+ }
+ else
+ {
+ pte = orig_pte;
+
+ if ( !p2m_table(pte) )
+ pte.bits = 0;
+
+ if ( p2m_valid(pte) )
+ {
+ rc = p2m_mem_access_radix_set(p2m, paddr_to_pfn(*addr), a);
+ if ( rc < 0 )
+ return rc;
+
+ p2m_set_permission(&pte, pte.p2m.type, a);
+ p2m_write_pte(entry, pte, flush_cache);
+ }
+
+ *addr += level_size;
+ *flush = true;
+ return P2M_ONE_PROGRESS;
+ }
}
BUG(); /* Should never get here */
@@ -776,6 +865,8 @@ static int apply_p2m_changes(struct domain *d,
unsigned int cur_root_table = ~0;
unsigned int cur_offset[4] = { ~0, };
unsigned int count = 0;
+ unsigned long start_gpfn = paddr_to_pfn(start_gpaddr),
+ end_gpfn = paddr_to_pfn(end_gpaddr);
bool_t flush = false;
bool_t flush_pt;
@@ -821,6 +912,22 @@ static int apply_p2m_changes(struct domain *d,
count = 0;
}
+ /*
+ * Preempt setting mem_access permissions as required by XSA-89,
+ * if it's not the last iteration.
+ */
+ if ( op == MEMACCESS && count )
+ {
+ uint32_t progress = paddr_to_pfn(addr) - start_gpfn + 1;
+
+ if ( (end_gpfn - start_gpfn) > progress && !(progress & mask)
+ && hypercall_preempt_check() )
+ {
+ rc = progress;
+ goto out;
+ }
+ }
+
if ( P2M_ROOT_PAGES > 1 )
{
int i;
@@ -1283,6 +1390,253 @@ void __init setup_virt_paging(void)
smp_call_function(setup_virt_paging_one, (void *)val, 1);
}
+bool_t p2m_mem_access_check(paddr_t gpa, vaddr_t gla, const struct npfec npfec)
+{
+ int rc;
+ bool_t violation;
+ xenmem_access_t xma;
+ mem_event_request_t *req;
+ struct vcpu *v = current;
+ struct p2m_domain *p2m = p2m_get_hostp2m(v->domain);
+
+ /* Mem_access is not in use. */
+ if ( !p2m->access_in_use )
+ return true;
+
+ rc = p2m_get_mem_access(v->domain, paddr_to_pfn(gpa), &xma);
+ if ( rc )
+ return true;
+
+ /* Now check for mem_access violation. */
+ switch ( xma )
+ {
+ case XENMEM_access_rwx:
+ violation = false;
+ break;
+ case XENMEM_access_rw:
+ violation = npfec.insn_fetch;
+ break;
+ case XENMEM_access_wx:
+ violation = npfec.read_access;
+ break;
+ case XENMEM_access_rx:
+ violation = npfec.write_access;
+ break;
+ case XENMEM_access_x:
+ violation = npfec.read_access || npfec.write_access;
+ break;
+ case XENMEM_access_w:
+ violation = npfec.read_access || npfec.insn_fetch;
+ break;
+ case XENMEM_access_r:
+ violation = npfec.write_access || npfec.insn_fetch;
+ break;
+ default:
+ case XENMEM_access_n:
+ violation = true;
+ break;
+ }
+
+ if ( !violation )
+ return true;
+
+ /* First, handle rx2rw and n2rwx conversion automatically. */
+ if ( npfec.write_access && xma == XENMEM_access_rx2rw )
+ {
+ rc = p2m_set_mem_access(v->domain, paddr_to_pfn(gpa), 1,
+ 0, ~0, XENMEM_access_rw);
+ return false;
+ }
+ else if ( xma == XENMEM_access_n2rwx )
+ {
+ rc = p2m_set_mem_access(v->domain, paddr_to_pfn(gpa), 1,
+ 0, ~0, XENMEM_access_rwx);
+ }
+
+ /* Otherwise, check if there is a memory event listener, and send the
message along */
+ if ( !mem_event_check_ring(&v->domain->mem_event->access) )
+ {
+ /* No listener */
+ if ( p2m->access_required )
+ {
+ gdprintk(XENLOG_INFO, "Memory access permissions failure, "
+ "no mem_event listener VCPU %d, dom %d\n",
+ v->vcpu_id, v->domain->domain_id);
+ domain_crash(v->domain);
+ }
+ else
+ {
+ /* n2rwx was already handled */
+ if ( xma != XENMEM_access_n2rwx )
+ {
+ /* A listener is not required, so clear the access
+ * restrictions. */
+ rc = p2m_set_mem_access(v->domain, paddr_to_pfn(gpa), 1,
+ 0, ~0, XENMEM_access_rwx);
+ }
+ }
+
+ /* No need to reinject */
+ return false;
+ }
+
+ req = xzalloc(mem_event_request_t);
+ if ( req )
+ {
+ req->reason = MEM_EVENT_REASON_VIOLATION;
+ if ( xma != XENMEM_access_n2rwx )
+ req->flags |= MEM_EVENT_FLAG_VCPU_PAUSED;
+ req->gfn = gpa >> PAGE_SHIFT;
+ req->offset = gpa & ((1 << PAGE_SHIFT) - 1);
+ req->gla = gla;
+ req->gla_valid = npfec.gla_valid;
+ req->access_r = npfec.read_access;
+ req->access_w = npfec.write_access;
+ req->access_x = npfec.insn_fetch;
+ if ( npfec_kind_in_gpt == npfec.kind )
+ req->fault_in_gpt = 1;
+ if ( npfec_kind_with_gla == npfec.kind )
+ req->fault_with_gla = 1;
+ req->vcpu_id = v->vcpu_id;
+
+ mem_access_send_req(v->domain, req);
+ xfree(req);
+ }
+
+ /* Pause the current VCPU */
+ if ( xma != XENMEM_access_n2rwx )
+ mem_event_vcpu_pause(v);
+
+ return false;
+}
+
+/* Set access type for a region of pfns.
+ * If start_pfn == -1ul, sets the default access type */
+long p2m_set_mem_access(struct domain *d, unsigned long pfn, uint32_t nr,
+ uint32_t start, uint32_t mask, xenmem_access_t access)
+{
+ struct p2m_domain *p2m = p2m_get_hostp2m(d);
+ p2m_access_t a;
+ long rc = 0;
+
+ static const p2m_access_t memaccess[] = {
+#define ACCESS(ac) [XENMEM_access_##ac] = p2m_access_##ac
+ ACCESS(n),
+ ACCESS(r),
+ ACCESS(w),
+ ACCESS(rw),
+ ACCESS(x),
+ ACCESS(rx),
+ ACCESS(wx),
+ ACCESS(rwx),
+ ACCESS(rx2rw),
+ ACCESS(n2rwx),
+#undef ACCESS
+ };
+
+ switch ( access )
+ {
+ case 0 ... ARRAY_SIZE(memaccess) - 1:
+ a = memaccess[access];
+ break;
+ case XENMEM_access_default:
+ a = p2m->default_access;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ /*
+ * Flip access_in_use to true when a permission is set, as to prevent
+ * allocating or inserting super-pages.
+ */
+ p2m->access_in_use = true;
+
+ /* If request to set default access. */
+ if ( pfn == ~0ul )
+ {
+ p2m->default_access = a;
+ return 0;
+ }
+
+ rc = apply_p2m_changes(d, MEMACCESS,
+ pfn_to_paddr(pfn+start), pfn_to_paddr(pfn+nr),
+ 0, MATTR_MEM, mask, 0, a);
+
+ if ( rc < 0 )
+ return rc;
+ else if ( rc > 0 )
+ return start + rc;
+
+ return 0;
+}
+
+int p2m_get_mem_access(struct domain *d, unsigned long gpfn,
+ xenmem_access_t *access)
+{
+ struct p2m_domain *p2m = p2m_get_hostp2m(d);
+ void *i;
+ unsigned int index;
+
+ static const xenmem_access_t memaccess[] = {
+#define ACCESS(ac) [p2m_access_##ac] = XENMEM_access_##ac
+ ACCESS(n),
+ ACCESS(r),
+ ACCESS(w),
+ ACCESS(rw),
+ ACCESS(x),
+ ACCESS(rx),
+ ACCESS(wx),
+ ACCESS(rwx),
+ ACCESS(rx2rw),
+ ACCESS(n2rwx),
+#undef ACCESS
+ };
+
+ /* If no setting was ever set, just return rwx. */
+ if ( !p2m->access_in_use )
+ {
+ *access = XENMEM_access_rwx;
+ return 0;
+ }
+
+ /* If request to get default access */
+ if ( gpfn == ~0ull )
+ {
+ *access = memaccess[p2m->default_access];
+ return 0;
+ }
+
+ spin_lock(&p2m->lock);
+ i = radix_tree_lookup(&p2m->mem_access_settings, gpfn);
+ spin_unlock(&p2m->lock);
+
+ if ( !i )
+ {
+ /*
+ * No setting was found in the Radix tree. Check if the
+ * entry exists in the page-tables.
+ */
+ paddr_t maddr = p2m_lookup(d, gpfn << PAGE_SHIFT, NULL);
+ if ( INVALID_PADDR == maddr )
+ return -ESRCH;
+
+ /* If entry exists then its rwx. */
+ *access = XENMEM_access_rwx;
+ }
+ else
+ {
+ /* Setting was found in the Radix tree. */
+ index = radix_tree_ptr_to_int(i);
+ if ( index >= ARRAY_SIZE(memaccess) )
+ return -ERANGE;
+
+ *access = memaccess[index];
+ }
+
+ return 0;
+}
+
/*
* Local variables:
* mode: C
diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index cda0523..ea695f9 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -30,6 +30,7 @@
#include <xen/hypercall.h>
#include <xen/softirq.h>
#include <xen/domain_page.h>
+#include <xen/mem_access.h>
#include <public/sched.h>
#include <public/xen.h>
#include <asm/event.h>
@@ -1869,11 +1870,31 @@ static void do_trap_data_abort_guest(struct
cpu_user_regs *regs,
info.gva = READ_SYSREG64(FAR_EL2);
#endif
- if (dabt.s1ptw)
+ rc = gva_to_ipa(info.gva, &info.gpa);
+ if ( -EFAULT == rc )
goto bad_data_abort;
- rc = gva_to_ipa(info.gva, &info.gpa);
- if ( rc == -EFAULT )
+ switch ( dabt.dfsc & 0x3f )
+ {
+ case FSC_FLT_PERM ... FSC_FLT_PERM + 3:
+ {
+ const struct npfec npfec = {
+ .read_access = 1,
+ .write_access = dabt.write,
+ .gla_valid = 1,
+ .kind = dabt.s1ptw ? npfec_kind_in_gpt : npfec_kind_with_gla
+ };
+
+ rc = p2m_mem_access_check(info.gpa, info.gva, npfec);
+
+ /* Trap was triggered by mem_access, work here is done */
+ if ( !rc )
+ return;
+ }
+ break;
+ }
+
+ if ( dabt.s1ptw )
goto bad_data_abort;
/* XXX: Decode the instruction if ISS is not valid */
diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
index db12026..2baa6bf 100644
--- a/xen/include/asm-arm/p2m.h
+++ b/xen/include/asm-arm/p2m.h
@@ -4,6 +4,7 @@
#include <xen/mm.h>
#include <xen/radix-tree.h>
#include <public/mem_event.h> /* for mem_event_response_t */
+#include <public/memory.h>
#include <xen/p2m-common.h>
@@ -246,6 +247,20 @@ static inline bool_t p2m_mem_event_sanity_check(struct
domain *d)
return 1;
}
+/* Send mem event based on the access. Boolean return value indicates if trap
+ * needs to be injected into guest. */
+bool_t p2m_mem_access_check(paddr_t gpa, vaddr_t gla, const struct npfec
npfec);
+
+/* Set access type for a region of pfns.
+ * If start_pfn == -1ul, sets the default access type */
+long p2m_set_mem_access(struct domain *d, unsigned long start_pfn, uint32_t nr,
+ uint32_t start, uint32_t mask, xenmem_access_t access);
+
+/* Get access type for a pfn
+ * If pfn == -1ul, gets the default access type */
+int p2m_get_mem_access(struct domain *d, unsigned long pfn,
+ xenmem_access_t *access);
+
#endif /* _XEN_P2M_H */
/*
--
2.1.0
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