[PATCH v3 10/11] vmware: set cpu capabilities during platform initialization

From: Juergen Gross
Date: Tue Apr 18 2017 - 02:32:10 EST


There is no need to set the same capabilities for each cpu
individually. This can be done for all cpus in platform initialization.

Cc: Alok Kataria <akataria@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Acked-by: Alok Kataria <akataria@xxxxxxxxxx>
---
arch/x86/kernel/cpu/vmware.c | 39 ++++++++++++++++++++-------------------
1 file changed, 20 insertions(+), 19 deletions(-)

diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
index 22403a28caf5..40ed26852ebd 100644
--- a/arch/x86/kernel/cpu/vmware.c
+++ b/arch/x86/kernel/cpu/vmware.c
@@ -113,6 +113,24 @@ static void __init vmware_paravirt_ops_setup(void)
#define vmware_paravirt_ops_setup() do {} while (0)
#endif

+/*
+ * VMware hypervisor takes care of exporting a reliable TSC to the guest.
+ * Still, due to timing difference when running on virtual cpus, the TSC can
+ * be marked as unstable in some cases. For example, the TSC sync check at
+ * bootup can fail due to a marginal offset between vcpus' TSCs (though the
+ * TSCs do not drift from each other). Also, the ACPI PM timer clocksource
+ * is not suitable as a watchdog when running on a hypervisor because the
+ * kernel may miss a wrap of the counter if the vcpu is descheduled for a
+ * long time. To skip these checks at runtime we set these capability bits,
+ * so that the kernel could just trust the hypervisor with providing a
+ * reliable virtual TSC that is suitable for timekeeping.
+ */
+static void __init vmware_set_capabilities(void)
+{
+ setup_force_cpu_cap(X86_FEATURE_CONSTANT_TSC);
+ setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
+}
+
static void __init vmware_platform_setup(void)
{
uint32_t eax, ebx, ecx, edx;
@@ -152,6 +170,8 @@ static void __init vmware_platform_setup(void)
#ifdef CONFIG_X86_IO_APIC
no_timer_check = 1;
#endif
+
+ vmware_set_capabilities();
}

/*
@@ -176,24 +196,6 @@ static uint32_t __init vmware_platform(void)
return 0;
}

-/*
- * VMware hypervisor takes care of exporting a reliable TSC to the guest.
- * Still, due to timing difference when running on virtual cpus, the TSC can
- * be marked as unstable in some cases. For example, the TSC sync check at
- * bootup can fail due to a marginal offset between vcpus' TSCs (though the
- * TSCs do not drift from each other). Also, the ACPI PM timer clocksource
- * is not suitable as a watchdog when running on a hypervisor because the
- * kernel may miss a wrap of the counter if the vcpu is descheduled for a
- * long time. To skip these checks at runtime we set these capability bits,
- * so that the kernel could just trust the hypervisor with providing a
- * reliable virtual TSC that is suitable for timekeeping.
- */
-static void vmware_set_cpu_features(struct cpuinfo_x86 *c)
-{
- set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);
- set_cpu_cap(c, X86_FEATURE_TSC_RELIABLE);
-}
-
/* Checks if hypervisor supports x2apic without VT-D interrupt remapping. */
static bool __init vmware_legacy_x2apic_available(void)
{
@@ -206,7 +208,6 @@ static bool __init vmware_legacy_x2apic_available(void)
const __refconst struct hypervisor_x86 x86_hyper_vmware = {
.name = "VMware",
.detect = vmware_platform,
- .set_cpu_features = vmware_set_cpu_features,
.init_platform = vmware_platform_setup,
.x2apic_available = vmware_legacy_x2apic_available,
};
--
2.12.0