Re: [Qemu-devel][PATCH] x86/cpu: Use max host physical address if -cpu max option is applied

[Paolo Bonzini]

On 13/01/21 10:04, Yang Weijiang wrote:
QEMU option -cpu max(max_features) means "Enables all features supported by
the accelerator in the current host", this looks true for all the features
except guest max physical address width, so add this patch to enable it.
Signed-off-by: Yang Weijiang <weijiang.y...@intel.com>
---
  target/i386/cpu.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 35459a38bb..b5943406f7 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -6673,7 +6673,7 @@ static void x86_cpu_realizefn(DeviceState *dev, Error 
**errp)
                  warned = true;
              }
  
-            if (cpu->host_phys_bits) {
+            if (cpu->host_phys_bits || cpu->max_features) {
                  /* The user asked for us to use the host physical bits */
                  cpu->phys_bits = host_phys_bits;
                  if (cpu->host_phys_bits_limit &&


Can you check if this works?

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 35459a38bb..72a79e6019 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -4319,6 +4319,7 @@ static void max_x86_cpu_initfn(Object *obj)
         if (lmce_supported()) {
             object_property_set_bool(OBJECT(cpu), "lmce", true, 
&error_abort);
         }
+        object_property_set_bool(OBJECT(cpu), "host-phys-bits", true, 
&error_abort);
     } else {
         object_property_set_str(OBJECT(cpu), "vendor", CPUID_VENDOR_AMD,
                                 &error_abort);


It should allow people to use -cpu max,host-phys-bits=false.

Thanks,

Paolo