[Qemu-devel] [PATCH 5/5] x86: Set physical address bits based on host

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

A special case based on the previous phys-bits property; if it's
the magic value 0 then use the hosts capabilities.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 target-i386/cpu.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index c3bbf8e..e03e48f 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -2609,7 +2609,21 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
             /* 64 bit processor, 48 bits virtual, configurable
              * physical bits.
              */
-            *eax = 0x00003000 + cpu->phys_bits;
+            if (cpu->phys_bits != 0) {
+                *eax = 0x00003000 + cpu->phys_bits;
+            } else {
+                /* phys_bits set to 0 -> Try and read the host, again
+                 * fall back to the magic 40 qemu used for a long time
+                 * Note: This is setting the virtual size as well from
+                 * the host; TODO: Split that out
+                 */
+                uint32_t _eax;
+                *eax = 0x00003028; /* 48 bits virtual, 40 bits physical */
+                host_cpuid(0x80000000, 0, &_eax, NULL, NULL, NULL);
+                if (_eax >= 0x80000008) {
+                    host_cpuid(0x80000008, 0, eax, NULL, NULL, NULL);
+                }
+            }
         } else {
             if (env->features[FEAT_1_EDX] & CPUID_PSE36) {
                 *eax = 0x00000024; /* 36 bits physical */
-- 
2.7.4