[RFC PATCH 4/4] xen/arm: Use sanitize values for p2m

[Bertrand Marquis <bertrand.marquis@xxxxxxx>]

Replace the code in p2m trying to find a sane value for the VMID size
supported and the PAR to use. We are now using the boot cpuinfo as the
values there are sanitized during boot and the value for those
parameters is now the safest possible value on the system.

On arm32, the system will panic if there are different types of core so
those checks were not needed anyway.

Signed-off-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
---
 xen/arch/arm/p2m.c | 30 ++++++++++--------------------
 1 file changed, 10 insertions(+), 20 deletions(-)

diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index d414c4feb9..2536a86a13 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -2030,31 +2030,21 @@ void __init setup_virt_paging(void)
         [7] = { 0 }  /* Invalid */
     };
 
-    unsigned int i, cpu;
+    unsigned int i;
     unsigned int pa_range = 0x10; /* Larger than any possible value */
-    bool vmid_8_bit = false;
-
-    for_each_online_cpu ( cpu )
-    {
-        const struct cpuinfo_arm *info = &cpu_data[cpu];
 
-        /*
-         * Restrict "p2m_ipa_bits" if needed. As P2M table is always configured
-         * with IPA bits == PA bits, compare against "pabits".
-         */
-        if ( pa_range_info[info->mm64.pa_range].pabits < p2m_ipa_bits )
-            p2m_ipa_bits = pa_range_info[info->mm64.pa_range].pabits;
-
-        /* Set a flag if the current cpu does not support 16 bit VMIDs. */
-        if ( info->mm64.vmid_bits != MM64_VMID_16_BITS_SUPPORT )
-            vmid_8_bit = true;
-    }
+    /*
+     * Restrict "p2m_ipa_bits" if needed. As P2M table is always configured
+     * with IPA bits == PA bits, compare against "pabits".
+     */
+    if ( pa_range_info[boot_cpu_data.mm64.pa_range].pabits < p2m_ipa_bits )
+        p2m_ipa_bits = pa_range_info[boot_cpu_data.mm64.pa_range].pabits;
 
     /*
-     * If the flag is not set then it means all CPUs support 16-bit
-     * VMIDs.
+     * cpu info sanitization made sure we support 16bits VMID only if all
+     * cores are supporting it.
      */
-    if ( !vmid_8_bit )
+    if ( boot_cpu_data.mm64.vmid_bits == MM64_VMID_16_BITS_SUPPORT )
         max_vmid = MAX_VMID_16_BIT;
 
     /* Choose suitable "pa_range" according to the resulted "p2m_ipa_bits". */
-- 
2.17.1