[v4,5/7] xen/arm: Use sanitize values for p2m

Commit Message

Bertrand Marquis Sept. 16, 2021, 6:25 a.m. UTC

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.

Signed-off-by: Bertrand Marquis <[e-mail]>
Reviewed-by: Stefano Stabellini <[e-mail]>
---
Changes in v4: none
Changes in v3: drop arm32 mention in commmit message
Changes in v2:
 - use system_cpuinfo
---
 xen/arch/arm/p2m.c | 30 ++++++++++--------------------
 1 file changed, 10 insertions(+), 20 deletions(-)

Patch

diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 6e01e83967..8b20b43077 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -2042,31 +2042,21 @@  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[system_cpuinfo.mm64.pa_range].pabits < p2m_ipa_bits )
+        p2m_ipa_bits = pa_range_info[system_cpuinfo.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 ( system_cpuinfo.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". */