[PATCH RFC 2/4] Add yield hypercall for KVM guests

Srivatsa Vaddagiri
2010-07-26T06:14:45Z

Add KVM hypercall for yielding vcpu timeslice.

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>

---
arch/x86/include/asm/kvm_para.h | 1 +
arch/x86/kvm/x86.c | 7 ++++++-
include/linux/kvm.h | 1 +
include/linux/kvm_para.h | 1 +
4 files changed, 9 insertions(+), 1 deletion(-)

Index: current/arch/x86/include/asm/kvm_para.h
===================================================================
--- current.orig/arch/x86/include/asm/kvm_para.h
+++ current/arch/x86/include/asm/kvm_para.h
@@ -16,6 +16,7 @@
#define KVM_FEATURE_CLOCKSOURCE 0
#define KVM_FEATURE_NOP_IO_DELAY 1
#define KVM_FEATURE_MMU_OP 2
+#define KVM_FEATURE_YIELD 4
/* This indicates that the new set of kvmclock msrs
* are available. The use of 0x11 and 0x12 is deprecated
*/
Index: current/arch/x86/kvm/x86.c
===================================================================
--- current.orig/arch/x86/kvm/x86.c
+++ current/arch/x86/kvm/x86.c
@@ -1618,6 +1618,7 @@ int kvm_dev_ioctl_check_extension(long e
case KVM_CAP_PCI_SEGMENT:
case KVM_CAP_DEBUGREGS:
case KVM_CAP_X86_ROBUST_SINGLESTEP:
+ case KVM_CAP_YIELD_HYPERCALL:
r = 1;
break;
case KVM_CAP_COALESCED_MMIO:
@@ -1993,7 +1994,8 @@ static void do_cpuid_ent(struct kvm_cpui
entry->eax = (1 << KVM_FEATURE_CLOCKSOURCE) |
(1 << KVM_FEATURE_NOP_IO_DELAY) |
(1 << KVM_FEATURE_CLOCKSOURCE2) |
- (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT);
+ (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) |
+ (1 << KVM_FEATURE_YIELD);
entry->ebx = 0;
entry->ecx = 0;
entry->edx = 0;
@@ -4245,6 +4247,9 @@ int kvm_emulate_hypercall(struct kvm_vcp
case KVM_HC_MMU_OP:
r = kvm_pv_mmu_op(vcpu, a0, hc_gpa(vcpu, a1, a2), &ret);
break;
+ case KVM_HC_YIELD:
+ ret = 0;
+ yield();
default:
ret = -KVM_ENOSYS;
break;
Index: current/include/linux/kvm.h
===================================================================
--- current.orig/include/linux/kvm.h
+++ current/include/linux/kvm.h
@@ -524,6 +524,7 @@ struct kvm_enable_cap {
#define KVM_CAP_PPC_OSI 52
#define KVM_CAP_PPC_UNSET_IRQ 53
#define KVM_CAP_ENABLE_CAP 54
+#define KVM_CAP_YIELD_HYPERCALL 55

#ifdef KVM_CAP_IRQ_ROUTING

Index: current/include/linux/kvm_para.h
===================================================================
--- current.orig/include/linux/kvm_para.h
+++ current/include/linux/kvm_para.h
@@ -17,6 +17,7 @@

#define KVM_HC_VAPIC_POLL_IRQ 1
#define KVM_HC_MMU_OP 2
+#define KVM_HC_YIELD 3

/*
* hypercalls use architecture specific