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[Qemu-devel] [patch 2/2] kvm: introduce cpu flag to enable cpu frequency
From: |
Marcelo Tosatti |
Subject: |
[Qemu-devel] [patch 2/2] kvm: introduce cpu flag to enable cpu frequency changes via hypercall |
Date: |
Thu, 02 Feb 2017 15:53:34 -0200 |
User-agent: |
quilt/0.60-1 |
Guests with DPDK, whose vcpus run isolated on physical CPUs, want
to control the frequency of such physical CPUs.
Introduce a allow-freq-hc CPU flag to enable such hypercalls.
Signed-off-by: Marcelo Tosatti <address@hidden>
---
target/i386/cpu.c | 1 +
target/i386/cpu.h | 6 ++++++
target/i386/kvm.c | 29 +++++++++++++++++++++++++++++
target/i386/kvm_i386.h | 1 +
4 files changed, 37 insertions(+)
Index: qemu/target/i386/cpu.c
===================================================================
--- qemu.orig/target/i386/cpu.c 2017-01-31 09:18:52.944948296 -0200
+++ qemu/target/i386/cpu.c 2017-01-31 09:47:58.050671578 -0200
@@ -3659,6 +3659,7 @@
DEFINE_PROP_BOOL("lmce", X86CPU, enable_lmce, false),
DEFINE_PROP_BOOL("l3-cache", X86CPU, enable_l3_cache, true),
DEFINE_PROP_BOOL("vmware-cpuid-freq", X86CPU, vmware_cpuid_freq, true),
+ DEFINE_PROP_BOOL("allow-freq-hc", X86CPU, allow_freq_hc, false),
DEFINE_PROP_END_OF_LIST()
};
Index: qemu/target/i386/cpu.h
===================================================================
--- qemu.orig/target/i386/cpu.h 2017-01-31 09:18:52.944948296 -0200
+++ qemu/target/i386/cpu.h 2017-01-31 09:47:58.051671580 -0200
@@ -1243,6 +1243,12 @@
*/
bool enable_l3_cache;
+ /* Direct frequency hypercalls from guest userspace can be
+ * enabled/disabled via cpu option 'allow_freq_hc=on/off'.
+ * It is disabled by default.
+ */
+ bool allow_freq_hc;
+
/* Compatibility bits for old machine types: */
bool enable_cpuid_0xb;
Index: qemu/target/i386/kvm.c
===================================================================
--- qemu.orig/target/i386/kvm.c 2017-01-31 09:18:52.944948296 -0200
+++ qemu/target/i386/kvm.c 2017-01-31 10:05:01.546855265 -0200
@@ -163,6 +163,11 @@
has_x2apic_api);
}
+bool kvm_has_allow_freq_hc(void)
+{
+ return kvm_check_extension(kvm_state, KVM_CAP_ALLOW_FREQ_HC);
+}
+
static int kvm_get_tsc(CPUState *cs)
{
X86CPU *cpu = X86_CPU(cs);
@@ -692,6 +697,15 @@
return 0;
}
+static int kvm_set_vcpu_allow_freq(X86CPU *cpu)
+{
+ struct kvm_vcpu_allow_freq fr;
+
+ fr.enable = 1;
+
+ return kvm_vcpu_ioctl(CPU(cpu), KVM_SET_VCPU_ALLOW_FREQ_HC, &fr);
+}
+
static Error *invtsc_mig_blocker;
#define KVM_MAX_CPUID_ENTRIES 100
@@ -1040,6 +1054,21 @@
has_msr_tsc_aux = false;
}
+ if (cpu->allow_freq_hc) {
+ int ret;
+
+ if (!kvm_has_allow_freq_hc()) {
+ error_report("kvm: allow freq hypercall not supported");
+ return -ENOTSUP;
+ }
+
+ ret = kvm_set_vcpu_allow_freq(cpu);
+ if (ret) {
+ error_report("kvm: kvm_set_allow_freq failure, ret=%d", ret);
+ return ret;
+ }
+ }
+
return 0;
fail:
Index: qemu/target/i386/kvm_i386.h
===================================================================
--- qemu.orig/target/i386/kvm_i386.h 2017-01-31 09:18:52.944948296 -0200
+++ qemu/target/i386/kvm_i386.h 2017-01-31 09:47:58.052671582 -0200
@@ -21,6 +21,7 @@
void kvm_synchronize_all_tsc(void);
void kvm_arch_reset_vcpu(X86CPU *cs);
void kvm_arch_do_init_vcpu(X86CPU *cs);
+bool kvm_has_allow_freq_hc(void);
int kvm_device_pci_assign(KVMState *s, PCIHostDeviceAddress *dev_addr,
uint32_t flags, uint32_t *dev_id);