GuestPhysBits (cpuid leaf 80000008, eax[23:16]) is intended for software
use. Physical CPUs do not set that field. The current code which
propagates the host's GuestPhysBits to the guest's PhysBits does not
make sense. Remove it.
Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
---
arch/x86/kvm/cpuid.c | 32 ++++++++++++++------------------
1 file changed, 14 insertions(+), 18 deletions(-)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index adba49afb5fe..c638b5fb2144 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -1221,26 +1221,22 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
entry->eax = entry->ebx = entry->ecx = 0;
break;
case 0x80000008: {
- unsigned g_phys_as = (entry->eax >> 16) & 0xff;
- unsigned virt_as = max((entry->eax >> 8) & 0xff, 48U);
- unsigned phys_as = entry->eax & 0xff;
+ unsigned int virt_as = max((entry->eax >> 8) & 0xff, 48U);
+ unsigned int phys_as;
- /*
- * If TDP (NPT) is disabled use the adjusted host MAXPHYADDR as
- * the guest operates in the same PA space as the host, i.e.
- * reductions in MAXPHYADDR for memory encryption affect shadow
- * paging, too.
- *
- * If TDP is enabled but an explicit guest MAXPHYADDR is not
- * provided, use the raw bare metal MAXPHYADDR as reductions to
- * the HPAs do not affect GPAs.
- */
- if (!tdp_enabled)
- g_phys_as = boot_cpu_data.x86_phys_bits;
- else if (!g_phys_as)
- g_phys_as = phys_as;
+ if (!tdp_enabled) {
+ /*
+ * If TDP (NPT) is disabled use the adjusted host
+ * MAXPHYADDR as the guest operates in the same PA
+ * space as the host, i.e. reductions in MAXPHYADDR
+ * for memory encryption affect shadow paging, too.
+ */
+ phys_as = boot_cpu_data.x86_phys_bits;
+ } else {
+ phys_as = entry->eax & 0xff;
+ }
- entry->eax = g_phys_as | (virt_as << 8);
+ entry->eax = phys_as | (virt_as << 8);
entry->ecx &= ~(GENMASK(31, 16) | GENMASK(11, 8));
entry->edx = 0;
cpuid_entry_override(entry, CPUID_8000_0008_EBX);
--
2.44.0
