[PATCH v3 3/3] altp2m: Implement p2m_get_mem_access for altp2m views

[Tamas K Lengyel <tlengyel@novetta.com>]

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

Signed-off-by: Tamas K Lengyel <tlengyel@novetta.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: Razvan Cojocaru <rcojocaru@bitdefender.com>
Cc: Stefano Stabellini <stefano.stabellini@citrix.com>
Cc: George Dunlap <george.dunlap@eu.citrix.com>
Cc: Keir Fraser <keir@xen.org>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
---
v3: Define a union over a memop field for the separate use during get and set
v2: Use unsigned int instead of unsigned long
    Use a single p2m pointer
---
 tools/libxc/include/xenctrl.h       |  3 ++-
 tools/libxc/xc_mem_access.c         | 10 ++++++----
 tools/tests/xen-access/xen-access.c |  5 ++++-
 xen/arch/arm/p2m.c                  |  4 ++--
 xen/arch/x86/mm/p2m.c               | 17 +++++++++++++++--
 xen/common/mem_access.c             | 10 +++++-----
 xen/include/public/memory.h         | 19 ++++++++++++++-----
 xen/include/xen/p2m-common.h        |  3 ++-
 8 files changed, 50 insertions(+), 21 deletions(-)

diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
index 1d656ac..a7cb3d5 100644
--- a/tools/libxc/include/xenctrl.h
+++ b/tools/libxc/include/xenctrl.h
@@ -2068,7 +2068,8 @@ 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 3634c39..884418f 100644
--- a/tools/libxc/xc_mem_access.c
+++ b/tools/libxc/xc_mem_access.c
@@ -35,7 +35,7 @@ int xc_set_mem_access(xc_interface *xch,
         .domid  = domain_id,
         .access = access,
         .pfn    = first_pfn,
-        .nr     = nr
+        .u.nr   = nr
     };
 
     return do_memory_op(xch, XENMEM_access_op, &mao, sizeof(mao));
@@ -44,14 +44,16 @@ 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,
+        .u.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 ef89246..d70955e 100644
--- a/tools/tests/xen-access/xen-access.c
+++ b/tools/tests/xen-access/xen-access.c
@@ -586,9 +586,12 @@ int main(int argc, char *argv[])
                     /*
                      * This serves no other purpose here then demonstrating the use of the API.
                      * At shutdown we have already reset all the permissions so really no use getting it again.
+                     * At shutdown the altp2m view is already destroyed so this query would fail.
                      */
                     xenmem_access_t 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 8568087..957fa57 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 int 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 226490a..d2efab7 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 )
             {
@@ -1917,7 +1919,8 @@ 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 int altp2m_idx,
+                       xenmem_access_t *access)
 {
     struct p2m_domain *p2m = p2m_get_hostp2m(d);
     p2m_type_t t;
@@ -1946,6 +1949,16 @@ int p2m_get_mem_access(struct domain *d, gfn_t gfn, xenmem_access_t *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];
+    }
+
     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 92ebead..f4e77c9 100644
--- a/xen/common/mem_access.c
+++ b/xen/common/mem_access.c
@@ -61,12 +61,12 @@ int mem_access_memop(unsigned long cmd,
     case XENMEM_access_op_set_access:
         rc = -EINVAL;
         if ( (mao.pfn != ~0ull) &&
-             (mao.nr < start_iter ||
-              ((mao.pfn + mao.nr - 1) < mao.pfn) ||
-              ((mao.pfn + mao.nr - 1) > domain_get_maximum_gpfn(d))) )
+             (mao.u.nr < start_iter ||
+              ((mao.pfn + mao.u.nr - 1) < mao.pfn) ||
+              ((mao.pfn + mao.u.nr - 1) > domain_get_maximum_gpfn(d))) )
             break;
 
-        rc = p2m_set_mem_access(d, _gfn(mao.pfn), mao.nr, start_iter,
+        rc = p2m_set_mem_access(d, _gfn(mao.pfn), mao.u.nr, start_iter,
                                 MEMOP_CMD_MASK, mao.access, 0);
         if ( rc > 0 )
         {
@@ -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.u.altp2m.idx, &access);
         if ( rc != 0 )
             break;
 
diff --git a/xen/include/public/memory.h b/xen/include/public/memory.h
index 4df38d6..c23c12b 100644
--- a/xen/include/public/memory.h
+++ b/xen/include/public/memory.h
@@ -423,11 +423,20 @@ struct xen_mem_access_op {
     /* xenmem_access_t */
     uint8_t access;
     domid_t domid;
-    /*
-     * Number of pages for set op
-     * Ignored on setting default access and other ops
-     */
-    uint32_t nr;
+    union {
+        /*
+         * Number of pages for set op
+         * Ignored on setting default access and other ops
+         */
+        uint32_t nr;
+        /*
+         * altp2m id used for get op, ignored for other ops
+         */
+        struct altp2m {
+            uint16_t idx;
+            uint16_t pad;
+        } altp2m;
+    } u;
     /*
      * First pfn for set op
      * pfn for get op
diff --git a/xen/include/xen/p2m-common.h b/xen/include/xen/p2m-common.h
index 8b70459..342bc4b 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 int altp2m_idx,
+                       xenmem_access_t *access);
 
 #endif /* _XEN_P2M_COMMON_H */
-- 
2.1.4