[Xen-devel] [PATCH 2/2] altp2m: Implement p2m_get_mem_access for altp2m views

[Tamas K Lengyel <tlengyel@xxxxxxxxxxx>]

Extend the existing get_mem_access memop to allow querying permissions in
altp2m views as well.

Signed-off-by: Tamas K Lengyel <tlengyel@xxxxxxxxxxx>
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
Cc: Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>
Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
Cc: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
Cc: Keir Fraser <keir@xxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 tools/libxc/include/xenctrl.h       |  3 ++-
 tools/libxc/xc_mem_access.c         |  8 +++++---
 tools/tests/xen-access/xen-access.c |  5 ++++-
 xen/arch/arm/p2m.c                  |  4 ++--
 xen/arch/x86/mm/p2m.c               | 23 +++++++++++++++++++----
 xen/common/mem_access.c             |  2 +-
 xen/include/xen/p2m-common.h        |  3 ++-
 7 files changed, 35 insertions(+), 13 deletions(-)

diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
index b4e57d8..09d9f62 100644
--- a/tools/libxc/include/xenctrl.h
+++ b/tools/libxc/include/xenctrl.h
@@ -2065,7 +2065,8 @@ int xc_set_mem_access(xc_interface *xch, domid_t 
domain_id,
  * Gets the mem access for the given page (returned in access on success)
  */
 int xc_get_mem_access(xc_interface *xch, domid_t domain_id,
-                      uint64_t pfn, xenmem_access_t *access);
+                      uint64_t pfn, uint16_t altp2m_idx,
+                      xenmem_access_t *access);
 
 /*
  * Instructions causing a mem_access violation can be emulated by Xen
diff --git a/tools/libxc/xc_mem_access.c b/tools/libxc/xc_mem_access.c
index d6fb409..a44865d 100644
--- a/tools/libxc/xc_mem_access.c
+++ b/tools/libxc/xc_mem_access.c
@@ -46,14 +46,16 @@ int xc_set_mem_access(xc_interface *xch,
 int xc_get_mem_access(xc_interface *xch,
                       domid_t domain_id,
                       uint64_t pfn,
+                      uint16_t altp2m_idx,
                       xenmem_access_t *access)
 {
     int rc;
     xen_mem_access_op_t mao =
     {
-        .op    = XENMEM_access_op_get_access,
-        .domid = domain_id,
-        .pfn   = pfn
+        .op         = XENMEM_access_op_get_access,
+        .domid      = domain_id,
+        .pfn        = pfn,
+        .altp2m_idx = altp2m_idx
     };
 
     rc = do_memory_op(xch, XENMEM_access_op, &mao, sizeof(mao));
diff --git a/tools/tests/xen-access/xen-access.c 
b/tools/tests/xen-access/xen-access.c
index 2300e9a..d9dda62 100644
--- a/tools/tests/xen-access/xen-access.c
+++ b/tools/tests/xen-access/xen-access.c
@@ -571,7 +571,10 @@ int main(int argc, char *argv[])
 
             switch (req.reason) {
             case VM_EVENT_REASON_MEM_ACCESS:
-                rc = xc_get_mem_access(xch, domain_id, req.u.mem_access.gfn, 
&access);
+                rc = xc_get_mem_access(xch, domain_id, req.u.mem_access.gfn,
+                                       ((req.flags & 
VM_EVENT_FLAG_ALTERNATE_P2M) ? req.altp2m_idx : 0),
+                                       &access
+                                       );
                 if (rc < 0)
                 {
                     ERROR("Error %d getting mem_access event\n", rc);
diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 8e9b4be..932c6e2 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -1666,7 +1666,7 @@ bool_t p2m_mem_access_check(paddr_t gpa, vaddr_t gla, 
const struct npfec npfec)
     if ( !p2m->mem_access_enabled )
         return true;
 
-    rc = p2m_get_mem_access(v->domain, _gfn(paddr_to_pfn(gpa)), &xma);
+    rc = p2m_get_mem_access(v->domain, _gfn(paddr_to_pfn(gpa)), 0, &xma);
     if ( rc )
         return true;
 
@@ -1847,7 +1847,7 @@ long p2m_set_mem_access(struct domain *d, gfn_t gfn, 
uint32_t nr,
     return 0;
 }
 
-int p2m_get_mem_access(struct domain *d, gfn_t gfn,
+int p2m_get_mem_access(struct domain *d, gfn_t gfn, unsigned long altp2m_idx,
                        xenmem_access_t *access)
 {
     int ret;
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 95bf7ce..18068e8 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -1572,7 +1572,9 @@ void p2m_mem_access_emulate_check(struct vcpu *v,
         bool_t violation = 1;
         const struct vm_event_mem_access *data = &rsp->u.mem_access;
 
-        if ( p2m_get_mem_access(v->domain, _gfn(data->gfn), &access) == 0 )
+        if ( p2m_get_mem_access(v->domain, _gfn(data->gfn),
+                                altp2m_active(v->domain) ? 
vcpu_altp2m(v).p2midx : 0,
+                                &access) == 0 )
         {
             switch ( access )
             {
@@ -1918,9 +1920,10 @@ long p2m_set_mem_access(struct domain *d, gfn_t gfn, 
uint32_t nr,
  * Get access type for a gfn.
  * If gfn == INVALID_GFN, gets the default access type.
  */
-int p2m_get_mem_access(struct domain *d, gfn_t gfn, xenmem_access_t *access)
+int p2m_get_mem_access(struct domain *d, gfn_t gfn, unsigned long altp2m_idx,
+                       xenmem_access_t *access)
 {
-    struct p2m_domain *p2m = p2m_get_hostp2m(d);
+    struct p2m_domain *hp2m = p2m_get_hostp2m(d), *p2m = NULL;
     p2m_type_t t;
     p2m_access_t a;
     mfn_t mfn;
@@ -1943,10 +1946,22 @@ int p2m_get_mem_access(struct domain *d, gfn_t gfn, 
xenmem_access_t *access)
     /* If request to get default access. */
     if ( gfn_x(gfn) == INVALID_GFN )
     {
-        *access = memaccess[p2m->default_access];
+        *access = memaccess[hp2m->default_access];
         return 0;
     }
 
+    /* altp2m view 0 is treated as the hostp2m */
+    if ( altp2m_idx )
+    {
+        if ( altp2m_idx >= MAX_ALTP2M ||
+             d->arch.altp2m_eptp[altp2m_idx] == INVALID_MFN )
+            return -EINVAL;
+
+        p2m = d->arch.altp2m_p2m[altp2m_idx];
+    }
+    else
+        p2m = hp2m;
+
     gfn_lock(p2m, gfn, 0);
     mfn = p2m->get_entry(p2m, gfn_x(gfn), &t, &a, 0, NULL, NULL);
     gfn_unlock(p2m, gfn, 0);
diff --git a/xen/common/mem_access.c b/xen/common/mem_access.c
index 0411443..a0345a6 100644
--- a/xen/common/mem_access.c
+++ b/xen/common/mem_access.c
@@ -88,7 +88,7 @@ int mem_access_memop(unsigned long cmd,
         if ( (mao.pfn > domain_get_maximum_gpfn(d)) && mao.pfn != ~0ull )
             break;
 
-        rc = p2m_get_mem_access(d, _gfn(mao.pfn), &access);
+        rc = p2m_get_mem_access(d, _gfn(mao.pfn), mao.altp2m_idx, &access);
         if ( rc != 0 )
             break;
 
diff --git a/xen/include/xen/p2m-common.h b/xen/include/xen/p2m-common.h
index 0643ad5..2835f24 100644
--- a/xen/include/xen/p2m-common.h
+++ b/xen/include/xen/p2m-common.h
@@ -56,6 +56,7 @@ long p2m_set_mem_access(struct domain *d, gfn_t gfn, uint32_t 
nr,
  * Get access type for a gfn.
  * If gfn == INVALID_GFN, gets the default access type.
  */
-int p2m_get_mem_access(struct domain *d, gfn_t gfn, xenmem_access_t *access);
+int p2m_get_mem_access(struct domain *d, gfn_t gfn, unsigned long altp2m_idx,
+                       xenmem_access_t *access);
 
 #endif /* _XEN_P2M_COMMON_H */
-- 
2.1.4


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