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[Qemu-devel] [PATCH 4/7] target-i386: kvm_cpu_fill_host(): No need to ch
From: |
Eduardo Habkost |
Subject: |
[Qemu-devel] [PATCH 4/7] target-i386: kvm_cpu_fill_host(): No need to check xlevel2 |
Date: |
Mon, 20 Jan 2014 14:41:11 -0200 |
There's no need to check CPU xlevel2 before calling
kvm_arch_get_supported_cpuid(s, 0xC0000001, 0, R_EDX), because:
* The kernel won't return any entry for 0xC0000000 if host CPU vendor
is not Centaur (See kvm_dev_ioctl_get_supported_cpuid() on the kernel
code)
* Similarly, the kernel won't return any entry for 0xC0000001 if
CPUID[0xC0000000].EAX is < 0xC0000001
* kvm_arch_get_supported_cpuid() will return 0 if no entry is returned
by the kernel for the requested leaf
For similar reasons, we can simply set x86_cpu_def->xlevel2 directly
instead of making it conditional, because it will be set to 0 CPU vendor
is not Centaur.
This will simplify the kvm_cpu_fill_host() code a little.
Signed-off-by: Eduardo Habkost <address@hidden>
---
target-i386/cpu.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)
diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 1a86bcf..8bc72c2 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -1173,13 +1173,11 @@ static void kvm_cpu_fill_host(x86_def_t *x86_cpu_def)
cpu_x86_fill_model_id(x86_cpu_def->model_id);
/* Call Centaur's CPUID instruction. */
- eax = kvm_arch_get_supported_cpuid(s, 0xC0000000, 0, R_EAX);
- if (eax >= 0xC0000001) {
- /* Support VIA max extended level */
- x86_cpu_def->xlevel2 = eax;
- x86_cpu_def->features[FEAT_C000_0001_EDX] =
- kvm_arch_get_supported_cpuid(s, 0xC0000001, 0, R_EDX);
- }
+ x86_cpu_def->xlevel2 =
+ kvm_arch_get_supported_cpuid(s, 0xC0000000, 0, R_EAX);
+ /* Support VIA max extended level */
+ x86_cpu_def->features[FEAT_C000_0001_EDX] =
+ kvm_arch_get_supported_cpuid(s, 0xC0000001, 0, R_EDX);
/* Other KVM-specific feature fields: */
x86_cpu_def->features[FEAT_SVM] =
--
1.8.4.2
- [Qemu-devel] [PATCH 0/7 RESEND] target-i386: Simplify kvm_cpu_fill_host() and kvm_check_features_against_host(), Eduardo Habkost, 2014/01/20
- [Qemu-devel] [PATCH 1/7] target-i386: kvm_cpu_fill_host(): Kill unused code, Eduardo Habkost, 2014/01/20
- [Qemu-devel] [PATCH 2/7] target-i386: kvm_cpu_fill_host(): No need to check level, Eduardo Habkost, 2014/01/20
- [Qemu-devel] [PATCH 3/7] target-i386: kvm_cpu_fill_host(): No need to check CPU vendor, Eduardo Habkost, 2014/01/20
- [Qemu-devel] [PATCH 4/7] target-i386: kvm_cpu_fill_host(): No need to check xlevel2,
Eduardo Habkost <=
- [Qemu-devel] [PATCH 5/7] target-i386: kvm_cpu_fill_host(): Set all feature words at end of function, Eduardo Habkost, 2014/01/20
- [Qemu-devel] [PATCH 6/7] target-i386: kvm_cpu_fill_host(): Fill feature words in a loop, Eduardo Habkost, 2014/01/20
- [Qemu-devel] [PATCH 7/7 v2] target-i386: kvm_check_features_against_host(): Kill feature word array, Eduardo Habkost, 2014/01/20
- Re: [Qemu-devel] [PATCH 0/7 RESEND] target-i386: Simplify kvm_cpu_fill_host() and kvm_check_features_against_host(), Eduardo Habkost, 2014/01/20