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Re: [Xen-devel] [PATCH 11/22] xen/arm: p2m: Find the memory attributes based on the p2m type

To: Stefano Stabellini <sstabellini@xxxxxxxxxx>

From: Julien Grall <julien.grall@xxxxxxx>

Date: Wed, 27 Jul 2016 21:15:02 +0100

Cc: proskurin@xxxxxxxxxxxxx, steve.capper@xxxxxxx, wei.chen@xxxxxxxxxx, xen-devel@xxxxxxxxxxxxx

Delivery-date: Wed, 27 Jul 2016 20:15:09 +0000

List-id: Xen developer discussion <xen-devel.lists.xen.org>

On 27/07/2016 18:55, Stefano Stabellini wrote:

On Wed, 27 Jul 2016, Julien Grall wrote:

Hi,

On 20/07/16 17:10, Julien Grall wrote:

Currently, mfn_to_p2m_entry is relying on the caller to provide the
correct memory attribute and will deduce the sharability based on it.

Some of the callers, such as p2m_create_table, are using same memory
attribute regardless the underlying p2m type. For instance, this will
lead to use change the memory attribute from MATTR_DEV to MATTR_MEM when
a MMIO superpage is shattered.

Furthermore, it makes more difficult to support different shareability
with the same memory attribute.

All the memory attributes could be deduced via the p2m type. This will
simplify the code by dropping one parameter.


I just noticed that I forgot to add my Signed-off-by. Stefano, can you add my
Signed-off-by while committing?


I could, but given that you need to resend some of the patches anyway,
it might be easier for me to wait for the next version.

I will resend the series tomorrow morning. Thank you for the review! Cheers,

---
    I am not sure whether p2m_direct_mmio_c (cacheable MMIO) should use
    the outer-shareability or inner-shareability. Any opinions?
---
 xen/arch/arm/p2m.c | 55
++++++++++++++++++++++++------------------------------
 1 file changed, 24 insertions(+), 31 deletions(-)

diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 999de2b..2f50b4f 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -325,8 +325,7 @@ static void p2m_set_permission(lpae_t *e, p2m_type_t t,
p2m_access_t a)
     }
 }

-static lpae_t mfn_to_p2m_entry(mfn_t mfn, unsigned int mattr,
-                               p2m_type_t t, p2m_access_t a)
+static lpae_t mfn_to_p2m_entry(mfn_t mfn, p2m_type_t t, p2m_access_t a)
 {
     /*
      * sh, xn and write bit will be defined in the following switches
@@ -335,7 +334,6 @@ static lpae_t mfn_to_p2m_entry(mfn_t mfn, unsigned int
mattr,
     lpae_t e = (lpae_t) {
         .p2m.af = 1,
         .p2m.read = 1,
-        .p2m.mattr = mattr,
         .p2m.table = 1,
         .p2m.valid = 1,
         .p2m.type = t,
@@ -343,18 +341,21 @@ static lpae_t mfn_to_p2m_entry(mfn_t mfn, unsigned int
mattr,

     BUILD_BUG_ON(p2m_max_real_type > (1 << 4));

-    switch (mattr)
+    switch ( t )
     {
-    case MATTR_MEM:
-        e.p2m.sh = LPAE_SH_INNER;
+    case p2m_mmio_direct_nc:
+        e.p2m.mattr = MATTR_DEV;
+        e.p2m.sh = LPAE_SH_OUTER;
         break;

-    case MATTR_DEV:
+    case p2m_mmio_direct_c:
+        e.p2m.mattr = MATTR_MEM;
         e.p2m.sh = LPAE_SH_OUTER;
         break;
+
     default:
-        BUG();
-        break;
+        e.p2m.mattr = MATTR_MEM;
+        e.p2m.sh = LPAE_SH_INNER;
     }

     p2m_set_permission(&e, t, a);
@@ -421,7 +422,7 @@ static int p2m_create_table(struct domain *d, lpae_t
*entry,
          */
          for ( i=0 ; i < LPAE_ENTRIES; i++ )
          {
-             pte = mfn_to_p2m_entry(mfn, MATTR_MEM, t,
p2m->default_access);
+             pte = mfn_to_p2m_entry(mfn, t, p2m->default_access);

              mfn = mfn_add(mfn, 1UL << (level_shift - LPAE_SHIFT));

@@ -445,7 +446,7 @@ static int p2m_create_table(struct domain *d, lpae_t
*entry,

     unmap_domain_page(p);

-    pte = mfn_to_p2m_entry(_mfn(page_to_mfn(page)), MATTR_MEM, p2m_invalid,
+    pte = mfn_to_p2m_entry(_mfn(page_to_mfn(page)), p2m_invalid,
                            p2m->default_access);

     p2m_write_pte(entry, pte, flush_cache);
@@ -666,7 +667,6 @@ static int apply_one_level(struct domain *d,
                            paddr_t *addr,
                            paddr_t *maddr,
                            bool_t *flush,
-                           int mattr,
                            p2m_type_t t,
                            p2m_access_t a)
 {
@@ -695,7 +695,7 @@ static int apply_one_level(struct domain *d,
                 return rc;

             /* New mapping is superpage aligned, make it */
-            pte = mfn_to_p2m_entry(_mfn(*maddr >> PAGE_SHIFT), mattr, t,
a);
+            pte = mfn_to_p2m_entry(_mfn(*maddr >> PAGE_SHIFT), t, a);
             if ( level < 3 )
                 pte.p2m.table = 0; /* Superpage entry */

@@ -915,7 +915,6 @@ static int apply_p2m_changes(struct domain *d,
                      gfn_t sgfn,
                      unsigned long nr,
                      mfn_t smfn,
-                     int mattr,
                      uint32_t mask,
                      p2m_type_t t,
                      p2m_access_t a)
@@ -1054,7 +1053,7 @@ static int apply_p2m_changes(struct domain *d,
                                   level, flush_pt, op,
                                   start_gpaddr, end_gpaddr,
                                   &addr, &maddr, &flush,
-                                  mattr, t, a);
+                                  t, a);
             if ( ret < 0 ) { rc = ret ; goto out; }
             count += ret;

@@ -1163,7 +1162,7 @@ out:
          * mapping.
          */
         apply_p2m_changes(d, REMOVE, sgfn, gfn - gfn_x(sgfn), smfn,
-                          mattr, 0, p2m_invalid,
d->arch.p2m.default_access);
+                          0, p2m_invalid, d->arch.p2m.default_access);
     }

     return rc;
@@ -1173,10 +1172,10 @@ static inline int p2m_insert_mapping(struct domain
*d,
                                      gfn_t start_gfn,
                                      unsigned long nr,
                                      mfn_t mfn,
-                                     int mattr, p2m_type_t t)
+                                     p2m_type_t t)
 {
     return apply_p2m_changes(d, INSERT, start_gfn, nr, mfn,
-                             mattr, 0, t, d->arch.p2m.default_access);
+                             0, t, d->arch.p2m.default_access);
 }

 static inline int p2m_remove_mapping(struct domain *d,
@@ -1186,8 +1185,7 @@ static inline int p2m_remove_mapping(struct domain *d,
 {
     return apply_p2m_changes(d, REMOVE, start_gfn, nr, mfn,
                              /* arguments below not used when removing
mapping */
-                             MATTR_MEM, 0, p2m_invalid,
-                             d->arch.p2m.default_access);
+                             0, p2m_invalid, d->arch.p2m.default_access);
 }

 int map_regions_rw_cache(struct domain *d,
@@ -1195,8 +1193,7 @@ int map_regions_rw_cache(struct domain *d,
                          unsigned long nr,
                          mfn_t mfn)
 {
-    return p2m_insert_mapping(d, gfn, nr, mfn,
-                              MATTR_MEM, p2m_mmio_direct_c);
+    return p2m_insert_mapping(d, gfn, nr, mfn, p2m_mmio_direct_c);
 }

 int unmap_regions_rw_cache(struct domain *d,
@@ -1212,8 +1209,7 @@ int map_mmio_regions(struct domain *d,
                      unsigned long nr,
                      mfn_t mfn)
 {
-    return p2m_insert_mapping(d, start_gfn, nr, mfn,
-                              MATTR_DEV, p2m_mmio_direct_nc);
+    return p2m_insert_mapping(d, start_gfn, nr, mfn, p2m_mmio_direct_nc);
 }

 int unmap_mmio_regions(struct domain *d,
@@ -1251,8 +1247,7 @@ int guest_physmap_add_entry(struct domain *d,
                             unsigned long page_order,
                             p2m_type_t t)
 {
-    return p2m_insert_mapping(d, gfn, (1 << page_order), mfn,
-                              MATTR_MEM, t);
+    return p2m_insert_mapping(d, gfn, (1 << page_order), mfn, t);
 }

 void guest_physmap_remove_page(struct domain *d,
@@ -1412,7 +1407,7 @@ int relinquish_p2m_mapping(struct domain *d)
     nr = gfn_x(p2m->max_mapped_gfn) - gfn_x(p2m->lowest_mapped_gfn);

     return apply_p2m_changes(d, RELINQUISH, p2m->lowest_mapped_gfn, nr,
-                             INVALID_MFN, MATTR_MEM, 0, p2m_invalid,
+                             INVALID_MFN, 0, p2m_invalid,
                              d->arch.p2m.default_access);
 }

@@ -1425,8 +1420,7 @@ int p2m_cache_flush(struct domain *d, gfn_t start,
unsigned long nr)
     end = gfn_min(end, p2m->max_mapped_gfn);

     return apply_p2m_changes(d, CACHEFLUSH, start, nr, INVALID_MFN,
-                             MATTR_MEM, 0, p2m_invalid,
-                             d->arch.p2m.default_access);
+                             0, p2m_invalid, d->arch.p2m.default_access);
 }

 mfn_t gfn_to_mfn(struct domain *d, gfn_t gfn)
@@ -1827,8 +1821,7 @@ long p2m_set_mem_access(struct domain *d, gfn_t gfn,
uint32_t nr,
     }

     rc = apply_p2m_changes(d, MEMACCESS, gfn_add(gfn, start),
-                           (nr - start), INVALID_MFN,
-                           MATTR_MEM, mask, 0, a);
+                           (nr - start), INVALID_MFN, mask, 0, a);
     if ( rc < 0 )
         return rc;
     else if ( rc > 0 )


--
Julien Grall

-- Julien Grall _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel

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