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KVM: x86: Refactor out-of-range logic to contain the madness

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Move all of the out-of-range logic into a single helper,
get_out_of_range_cpuid_entry(), to avoid an extra lookup of CPUID.0.0
and to provide a single location for documenting the out-of-range
behavior.

No functional change intended.

Cc: Jim Mattson <jmattson@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson
2020-03-04 17:34:36 -08:00
committed by Paolo Bonzini
parent 8d8923115f
commit 09c7431ed3
1 changed files with 29 additions and 18 deletions
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47
arch/x86/kvm/cpuid.c
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@@ -945,13 +945,19 @@ EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry);
* - HyperV: 0x40000000 - 0x400000ff * - HyperV: 0x40000000 - 0x400000ff
* - KVM: 0x40000100 - 0x400001ff * - KVM: 0x40000100 - 0x400001ff
*/ */
static bool cpuid_function_in_range(struct kvm_vcpu *vcpu, u32 function) static struct kvm_cpuid_entry2 *
get_out_of_range_cpuid_entry(struct kvm_vcpu *vcpu, u32 *fn_ptr, u32 index)
{ {
struct kvm_cpuid_entry2 *basic, *class; struct kvm_cpuid_entry2 *basic, *class;
u32 function = *fn_ptr;
basic = kvm_find_cpuid_entry(vcpu, 0, 0); basic = kvm_find_cpuid_entry(vcpu, 0, 0);
if (!basic) if (!basic)
return true; return NULL;
if (is_guest_vendor_amd(basic->ebx, basic->ecx, basic->edx) ||
is_guest_vendor_hygon(basic->ebx, basic->ecx, basic->edx))
return NULL;
if (function >= 0x40000000 && function <= 0x4fffffff) if (function >= 0x40000000 && function <= 0x4fffffff)
class = kvm_find_cpuid_entry(vcpu, function & 0xffffff00, 0); class = kvm_find_cpuid_entry(vcpu, function & 0xffffff00, 0);
@@ -960,7 +966,23 @@ static bool cpuid_function_in_range(struct kvm_vcpu *vcpu, u32 function)
else else
class = kvm_find_cpuid_entry(vcpu, function & 0x80000000, 0); class = kvm_find_cpuid_entry(vcpu, function & 0x80000000, 0);
return class && function <= class->eax; if (class && function <= class->eax)
return NULL;
/*
* Leaf specific adjustments are also applied when redirecting to the
* max basic entry, e.g. if the max basic leaf is 0xb but there is no
* entry for CPUID.0xb.index (see below), then the output value for EDX
* needs to be pulled from CPUID.0xb.1.
*/
*fn_ptr = basic->eax;
/*
* The class does not exist or the requested function is out of range;
* the effective CPUID entry is the max basic leaf. Note, the index of
* the original requested leaf is observed!
*/
return kvm_find_cpuid_entry(vcpu, basic->eax, index);
} }
bool kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx, bool kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx,
@@ -968,25 +990,14 @@ bool kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx,
{ {
u32 orig_function = *eax, function = *eax, index = *ecx; u32 orig_function = *eax, function = *eax, index = *ecx;
struct kvm_cpuid_entry2 *entry; struct kvm_cpuid_entry2 *entry;
struct kvm_cpuid_entry2 *max;
bool found; bool found;
entry = kvm_find_cpuid_entry(vcpu, function, index); entry = kvm_find_cpuid_entry(vcpu, function, index);
found = entry; found = entry;
/*
* Intel CPUID semantics treats any query for an out-of-range if (!entry && check_limit)
* leaf as if the highest basic leaf (i.e. CPUID.0H:EAX) were entry = get_out_of_range_cpuid_entry(vcpu, &function, index);
* requested. AMD CPUID semantics returns all zeroes for any
* undefined leaf, whether or not the leaf is in range.
*/
if (!entry && check_limit && !guest_cpuid_is_amd_or_hygon(vcpu) &&
!cpuid_function_in_range(vcpu, function)) {
max = kvm_find_cpuid_entry(vcpu, 0, 0);
if (max) {
function = max->eax;
entry = kvm_find_cpuid_entry(vcpu, function, index);
}
}
if (entry) { if (entry) {
*eax = entry->eax; *eax = entry->eax;
*ebx = entry->ebx; *ebx = entry->ebx;