Only invoke the underlying cpuid instruction if the real CPU might support

the leaf (<=cpuid_level) and always pass the subleaf.  Delete the
CPUID_LEAF() calls made superfluous by always passing the subleaf.

ok mlarkin@

diff --git a/sys/arch/amd64/amd64/vmm.c b/sys/arch/amd64/amd64/vmm.c
index edf7673..8740d47 100644 (file)
--- a/sys/arch/amd64/amd64/vmm.c
+++ b/sys/arch/amd64/amd64/vmm.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: vmm.c,v 1.301 2022/01/11 20:34:22 tobhe Exp $ */
+/*     $OpenBSD: vmm.c,v 1.302 2022/01/19 19:39:42 guenther Exp $      */
 /*
  * Copyright (c) 2014 Mike Larkin <mlarkin@openbsd.org>
  *
@@ -6770,7 +6770,11 @@ vmm_handle_cpuid(struct vcpu *vcpu)
                *rax = vmm_cpuid_level;
        }
 
-       CPUID_LEAF(*rax, 0, eax, ebx, ecx, edx);
+       /* we fake up values in the range (cpuid_level, vmm_cpuid_level] */
+       if (*rax <= cpuid_level || *rax > 0x80000000)
+               CPUID_LEAF(*rax, *rcx, eax, ebx, ecx, edx);
+       else
+               eax = ebx = ecx = edx = 0;
 
        switch (*rax) {
        case 0x00:      /* Max level and vendor ID */
@@ -6809,18 +6813,10 @@ vmm_handle_cpuid(struct vcpu *vcpu)
                *rdx = 0;
                break;
        case 0x04:      /* Deterministic cache info */
-               if (*rcx == 0) {
-                       *rax = eax & VMM_CPUID4_CACHE_TOPOLOGY_MASK;
-                       *rbx = ebx;
-                       *rcx = ecx;
-                       *rdx = edx;
-               } else {
-                       CPUID_LEAF(*rax, *rcx, eax, ebx, ecx, edx);
-                       *rax = eax & VMM_CPUID4_CACHE_TOPOLOGY_MASK;
-                       *rbx = ebx;
-                       *rcx = ecx;
-                       *rdx = edx;
-               }
+               *rax = eax & VMM_CPUID4_CACHE_TOPOLOGY_MASK;
+               *rbx = ebx;
+               *rcx = ecx;
+               *rdx = edx;
                break;
        case 0x05:      /* MONITOR/MWAIT (not supported) */
                DPRINTF("%s: function 0x05 (monitor/mwait) not supported\n",
@@ -6890,7 +6886,6 @@ vmm_handle_cpuid(struct vcpu *vcpu)
                        *rcx = 0;
                        *rdx = 0;
                } else {
-                       CPUID_LEAF(*rax, *rcx, eax, ebx, ecx, edx);
                        *rax = eax;
                        *rbx = ebx;
                        *rcx = ecx;
@@ -6989,13 +6984,17 @@ vmm_handle_cpuid(struct vcpu *vcpu)
                *rdx = curcpu()->ci_extcacheinfo[3];
                break;
        case 0x80000007:        /* apmi */
-               CPUID(0x80000007, *rax, *rbx, *rcx, *rdx);
+               *rax = eax;
+               *rbx = ebx;
+               *rcx = ecx;
+               *rdx = edx;
                break;
        case 0x80000008:        /* Phys bits info and topology (AMD) */
-               CPUID(0x80000008, *rax, *rbx, *rcx, *rdx);
-               *rbx &= VMM_AMDSPEC_EBX_MASK;
+               *rax = eax;
+               *rbx = ebx & VMM_AMDSPEC_EBX_MASK;
                /* Reset %rcx (topology) */
                *rcx = 0;
+               *rdx = edx;
                break;
        default:
                DPRINTF("%s: unsupported rax=0x%llx\n", __func__, *rax);