From: Keir Fraser <keir.fraser@citrix.com>
Date: Thu, 12 Jun 2008 15:05:35 +0000 (+0100)
Subject: x86/32on64: fix physical address restriction
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~14192^2~89
X-Git-Url: https://dgit.raspbian.org/%22http://www.example.com/cgi/%22/%22http:/www.example.com/cgi/%22?a=commitdiff_plain;h=aa6bc4f3e99e9b04bfe100f69be1c3d7399ea36e;p=xen.git

x86/32on64: fix physical address restriction

The allocation bit size setting wasn't working anymore after the
recent fix to properly use PAGE_SHIFT instead of PAGE_SIZE. This was
because the bit size implies a power-of-two range that's accessible,
but if all memory is accessible anyway (and its upper boundary is not
a power of two), the domain would either be needlessly restricted or
wouldn't be able to allocate as much memory as was intended for it
(specifically the case for Dom0 without dom0_mem= boot
parameter). Consequently, don't restrict the bit width if all memory
can be accessed.

To avoid needing to adjust this code in two places in the future (it
may need further touching when memory hotplug gets supported), fold
the logic into a function.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Keir Fraser <keir.fraser@citrix.com>
---

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 81c5ab6319..53fea02101 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -254,11 +254,7 @@ int switch_compat(struct domain *d)
                                  FIRST_RESERVED_GDT_PAGE)] = gdt_l1e;
     }
 
-    d->arch.physaddr_bitsize =
-        /* 2^n entries can be contained in guest's p2m mapping space */
-        fls((1UL << 32) - HYPERVISOR_COMPAT_VIRT_START(d)) - 3
-        /* 2^n pages -> 2^(n+PAGE_SHIFT) bits */
-        + PAGE_SHIFT;
+    domain_set_alloc_bitsize(d);
 
     return 0;
 
diff --git a/xen/arch/x86/domain_build.c b/xen/arch/x86/domain_build.c
index bf990a5ec6..8fce1eb907 100644
--- a/xen/arch/x86/domain_build.c
+++ b/xen/arch/x86/domain_build.c
@@ -353,14 +353,7 @@ int __init construct_dom0(
 #endif
     }
 
-#if defined(__x86_64__)
-    if ( is_pv_32on64_domain(d) )
-        d->arch.physaddr_bitsize =
-            /* 2^n entries can be contained in guest's p2m mapping space */
-            fls((1UL << 32) - HYPERVISOR_COMPAT_VIRT_START(d)) - 3
-            /* 2^n pages -> 2^(n+PAGE_SHIFT) bits */
-            + PAGE_SHIFT;
-#endif
+    domain_set_alloc_bitsize(d);
 
     /*
      * Why do we need this? The number of page-table frames depends on the 
diff --git a/xen/arch/x86/x86_64/mm.c b/xen/arch/x86/x86_64/mm.c
index 666d2dde78..febca9f455 100644
--- a/xen/arch/x86/x86_64/mm.c
+++ b/xen/arch/x86/x86_64/mm.c
@@ -168,7 +168,7 @@ void __init paging_init(void)
     if ( mpt_size > RDWR_COMPAT_MPT_VIRT_END - RDWR_COMPAT_MPT_VIRT_START )
         mpt_size = RDWR_COMPAT_MPT_VIRT_END - RDWR_COMPAT_MPT_VIRT_START;
     mpt_size &= ~((1UL << L2_PAGETABLE_SHIFT) - 1UL);
-    if ( m2p_compat_vstart + mpt_size < MACH2PHYS_COMPAT_VIRT_END )
+    if ( (m2p_compat_vstart + mpt_size) < MACH2PHYS_COMPAT_VIRT_END )
         m2p_compat_vstart = MACH2PHYS_COMPAT_VIRT_END - mpt_size;
     for ( i = 0; i < (mpt_size >> L2_PAGETABLE_SHIFT); i++ )
     {
@@ -472,9 +472,21 @@ int check_descriptor(const struct domain *dom, struct desc_struct *d)
     return 0;
 }
 
+void domain_set_alloc_bitsize(struct domain *d)
+{
+    if ( !is_pv_32on64_domain(d) ||
+         (MACH2PHYS_COMPAT_NR_ENTRIES(d) >= max_page) )
+        return;
+    d->arch.physaddr_bitsize =
+        /* 2^n entries can be contained in guest's p2m mapping space */
+        fls(MACH2PHYS_COMPAT_NR_ENTRIES(d)) - 1
+        /* 2^n pages -> 2^(n+PAGE_SHIFT) bits */
+        + PAGE_SHIFT;
+}
+
 unsigned int domain_clamp_alloc_bitsize(struct domain *d, unsigned int bits)
 {
-    if ( (d == NULL) || !is_pv_32on64_domain(d) )
+    if ( (d == NULL) || (d->arch.physaddr_bitsize == 0) )
         return bits;
     return min(d->arch.physaddr_bitsize, bits);
 }
diff --git a/xen/include/asm-x86/mm.h b/xen/include/asm-x86/mm.h
index e6b63e6772..43ec82cf2c 100644
--- a/xen/include/asm-x86/mm.h
+++ b/xen/include/asm-x86/mm.h
@@ -342,8 +342,10 @@ int steal_page(
 int map_ldt_shadow_page(unsigned int);
 
 #ifdef CONFIG_COMPAT
+void domain_set_alloc_bitsize(struct domain *d);
 unsigned int domain_clamp_alloc_bitsize(struct domain *d, unsigned int bits);
 #else
+# define domain_set_alloc_bitsize(d) ((void)0)
 # define domain_clamp_alloc_bitsize(d, b) (b)
 #endif