[Qemu-devel] [PATCH 09/15] i386: kvm: set CPUID_EXT_TSC_DEADLINE_TIMER on kvm_arch_get_supported_cpuid()

[Eduardo Habkost]

This moves the CPUID_EXT_TSC_DEADLINE_TIMER CPUID flag hacking from
kvm_arch_init_vcpu() to kvm_arch_get_supported_cpuid().

Full git grep for kvm_arch_get_supported_cpuid:

   kvm.h:uint32_t kvm_arch_get_supported_cpuid(KVMState *env, uint32_t function,
   target-i386/cpu.c:        x86_cpu_def->cpuid_7_0_ebx_features = 
kvm_arch_get_supported_cpuid(kvm_state, 0x7, 0, R_EBX);
   target-i386/cpu.c:            *eax = kvm_arch_get_supported_cpuid(s, 0xA, 
count, R_EAX);
   target-i386/cpu.c:            *ebx = kvm_arch_get_supported_cpuid(s, 0xA, 
count, R_EBX);
   target-i386/cpu.c:            *ecx = kvm_arch_get_supported_cpuid(s, 0xA, 
count, R_ECX);
   target-i386/cpu.c:            *edx = kvm_arch_get_supported_cpuid(s, 0xA, 
count, R_EDX);
   target-i386/cpu.c:            *eax = kvm_arch_get_supported_cpuid(s, 0xd, 
count, R_EAX);
   target-i386/cpu.c:            *ebx = kvm_arch_get_supported_cpuid(s, 0xd, 
count, R_EBX);
   target-i386/cpu.c:            *ecx = kvm_arch_get_supported_cpuid(s, 0xd, 
count, R_ECX);
   target-i386/cpu.c:            *edx = kvm_arch_get_supported_cpuid(s, 0xd, 
count, R_EDX);
   target-i386/kvm.c:uint32_t kvm_arch_get_supported_cpuid(KVMState *s, 
uint32_t function,
   target-i386/kvm.c:        cpuid_1_edx = kvm_arch_get_supported_cpuid(s, 1, 
0, R_EDX);
   target-i386/kvm.c:    env->cpuid_features &= kvm_arch_get_supported_cpuid(s, 
1, 0, R_EDX);
 * target-i386/kvm.c:    env->cpuid_ext_features &= 
kvm_arch_get_supported_cpuid(s, 1, 0, R_ECX);
   target-i386/kvm.c:    env->cpuid_ext2_features &= 
kvm_arch_get_supported_cpuid(s, 0x80000001,
   target-i386/kvm.c:    env->cpuid_ext3_features &= 
kvm_arch_get_supported_cpuid(s, 0x80000001,
   target-i386/kvm.c:    env->cpuid_svm_features  &= 
kvm_arch_get_supported_cpuid(s, 0x8000000A,
   target-i386/kvm.c:        kvm_arch_get_supported_cpuid(s, 
KVM_CPUID_FEATURES, 0, R_EAX);
   target-i386/kvm.c:            kvm_arch_get_supported_cpuid(s, 0xC0000001, 0, 
R_EDX);

Note that there is only one call for CPUID[1].ECX above (*), and it is
the one that gets hacked to include CPUID_EXT_TSC_DEADLINE_TIMER, so we
can simply make kvm_arch_get_supported_cpuid() set it, to let the rest
of the code know the flag can be safely set by QEMU.

One thing I was worrying about when doing this is that now
kvm_arch_get_supported_cpuid() depends on kvm_irqchip_in_kernel(). But
the 'kvm_kernel_irqchip' global variable is initialized during
kvm_init(), that is called very early, and kvm_init() is already a
requirement to run the GET_SUPPORTED_CPUID ioctl() (as kvm_init() is the
function that initializes the 'kvm_state' global variable).

Signed-off-by: Eduardo Habkost <address@hidden>
---
 target-i386/kvm.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 1f451e3..704ad33 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -201,6 +201,14 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s, 
uint32_t function,
          * GET_SUPPORTED_CPUID
          */
         ret |= CPUID_EXT_HYPERVISOR;
+        /* tsc-deadline flag is not returned by GET_SUPPORTED_CPUID, but it
+         * can be enabled if the kernel has KVM_CAP_TSC_DEADLINE_TIMER,
+         * and the irqchip is in the kernel.
+         */
+        if (kvm_irqchip_in_kernel() &&
+                kvm_check_extension(s, KVM_CAP_TSC_DEADLINE_TIMER)) {
+            ret |= CPUID_EXT_TSC_DEADLINE_TIMER;
+        }
     } else if (function == 0x80000001 && reg == R_EDX) {
         /* On Intel, kvm returns cpuid according to the Intel spec,
          * so add missing bits according to the AMD spec:
@@ -404,12 +412,7 @@ int kvm_arch_init_vcpu(CPUX86State *env)
 
     env->cpuid_features &= kvm_arch_get_supported_cpuid(s, 1, 0, R_EDX);
 
-    j = env->cpuid_ext_features & CPUID_EXT_TSC_DEADLINE_TIMER;
     env->cpuid_ext_features &= kvm_arch_get_supported_cpuid(s, 1, 0, R_ECX);
-    if (j && kvm_irqchip_in_kernel() &&
-        kvm_check_extension(s, KVM_CAP_TSC_DEADLINE_TIMER)) {
-        env->cpuid_ext_features |= CPUID_EXT_TSC_DEADLINE_TIMER;
-    }
 
     env->cpuid_ext2_features &= kvm_arch_get_supported_cpuid(s, 0x80000001,
                                                              0, R_EDX);
-- 
1.7.11.4