On Mon, Jan 07, 2013 at 01:42:53PM +0200, Gleb Natapov wrote:
On Mon, Jan 07, 2013 at 09:42:36AM -0200, Eduardo Habkost wrote:
On Sun, Jan 06, 2013 at 01:32:34PM +0200, Gleb Natapov wrote:
On Fri, Jan 04, 2013 at 08:01:02PM -0200, Eduardo Habkost wrote:
This is a cleanup that tries to solve two small issues:
- We don't need a separate kvm_pv_eoi_features variable just to keep a constant calculated at compile-time, and this style would require adding a separate variable (that's declared twice because of the CONFIG_KVM ifdef) for each feature that's going to be enabled/disable by machine-type compat code. - The pc-1.3 code is setting the kvm_pv_eoi flag on cpuid_kvm_features even when KVM is disabled at runtime. This small incosistency in the cpuid_kvm_features field isn't a problem today because cpuid_kvm_features is ignored by the TCG code, but it may cause unexpected problems later when refactoring the CPUID handling code.
This patch eliminates the kvm_pv_eoi_features variable and simply uses CONFIG_KVM and kvm_enabled() inside the enable_kvm_pv_eoi() compat function, so it enables kvm_pv_eoi only if KVM is enabled. I believe this makes the behavior of enable_kvm_pv_eoi() clearer and easier to understand.
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> --- Cc: kvm@vger.kernel.org Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Gleb Natapov <gleb@redhat.com> Cc: Marcelo Tosatti <mtosatti@redhat.com>
Changes v2: - Coding style fix --- target-i386/cpu.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/target-i386/cpu.c b/target-i386/cpu.c index 82685dc..e6435da 100644 --- a/target-i386/cpu.c +++ b/target-i386/cpu.c @@ -145,15 +145,17 @@ static uint32_t kvm_default_features = (1 << KVM_FEATURE_CLOCKSOURCE) | (1 << KVM_FEATURE_ASYNC_PF) | (1 << KVM_FEATURE_STEAL_TIME) | (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT); -static const uint32_t kvm_pv_eoi_features = (0x1 << KVM_FEATURE_PV_EOI); #else static uint32_t kvm_default_features = 0; -static const uint32_t kvm_pv_eoi_features = 0; #endif
void enable_kvm_pv_eoi(void) { - kvm_default_features |= kvm_pv_eoi_features; +#ifdef CONFIG_KVM You do not need ifdef here.
We need it because KVM_FEATURE_PV_EOI is available only if CONFIG_KVM is set.
I could also write it as:
if (kvm_enabled()) { #ifdef CONFIG_KVM kvm_default_features |= (1UL << KVM_FEATURE_PV_EOI); #endif }
But I find it less readable.
Why not define KVM_FEATURE_PV_EOI unconditionally?
It comes from the KVM kernel headers, that are included only if CONFIG_KVM is set, and probably won't even compile in non-Linux systems. I have a dejavu feeling. I believe we had this exact problem before, maybe about some other #defines that come from the Linux KVM headers and won't be available in non-Linux systems.
+ if (kvm_enabled()) { + kvm_default_features |= (1UL << KVM_FEATURE_PV_EOI); + } +#endif }
void host_cpuid(uint32_t function, uint32_t count, -- 1.7.11.7
-- Gleb.
-- Eduardo
-- Gleb.
-- Eduardo