KVM: Enhance guest cpuid management
The current cpuid management suffers from several problems, which inhibit
passing through the host feature set to the guest:
- No way to tell which features the host supports
While some features can be supported with no changes to kvm, others
need explicit support. That means kvm needs to vet the feature set
before it is passed to the guest.
- No support for indexed or stateful cpuid entries
Some cpuid entries depend on ecx as well as on eax, or on internal
state in the processor (running cpuid multiple times with the same
input returns different output). The current cpuid machinery only
supports keying on eax.
- No support for save/restore/migrate
The internal state above needs to be exposed to userspace so it can
be saved or migrated.
This patch adds extended cpuid support by means of three new ioctls:
- KVM_GET_SUPPORTED_CPUID: get all cpuid entries the host (and kvm)
supports
- KVM_SET_CPUID2: sets the vcpu's cpuid table
- KVM_GET_CPUID2: gets the vcpu's cpuid table, including hidden state
[avi: fix original KVM_SET_CPUID not removing nx on non-nx hosts as it did
before]
Signed-off-by: Dan Kenigsberg <danken@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/include/asm-x86/kvm.h b/include/asm-x86/kvm.h
index 4837d75..17afa81 100644
--- a/include/asm-x86/kvm.h
+++ b/include/asm-x86/kvm.h
@@ -151,5 +151,26 @@
struct kvm_cpuid_entry entries[0];
};
+struct kvm_cpuid_entry2 {
+ __u32 function;
+ __u32 index;
+ __u32 flags;
+ __u32 eax;
+ __u32 ebx;
+ __u32 ecx;
+ __u32 edx;
+ __u32 padding[3];
+};
+
+#define KVM_CPUID_FLAG_SIGNIFCANT_INDEX 1
+#define KVM_CPUID_FLAG_STATEFUL_FUNC 2
+#define KVM_CPUID_FLAG_STATE_READ_NEXT 4
+
+/* for KVM_SET_CPUID2 */
+struct kvm_cpuid2 {
+ __u32 nent;
+ __u32 padding;
+ struct kvm_cpuid_entry2 entries[0];
+};
#endif
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index fd4f900..b751552 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -224,6 +224,7 @@
#define KVM_CAP_MMU_SHADOW_CACHE_CONTROL 2
#define KVM_CAP_USER_MEMORY 3
#define KVM_CAP_SET_TSS_ADDR 4
+#define KVM_CAP_EXT_CPUID 5
/*
* ioctls for VM fds
@@ -241,6 +242,7 @@
#define KVM_CREATE_VCPU _IO(KVMIO, 0x41)
#define KVM_GET_DIRTY_LOG _IOW(KVMIO, 0x42, struct kvm_dirty_log)
#define KVM_SET_MEMORY_ALIAS _IOW(KVMIO, 0x43, struct kvm_memory_alias)
+#define KVM_GET_SUPPORTED_CPUID _IOWR(KVMIO, 0x48, struct kvm_cpuid2)
/* Device model IOC */
#define KVM_CREATE_IRQCHIP _IO(KVMIO, 0x60)
#define KVM_IRQ_LINE _IOW(KVMIO, 0x61, struct kvm_irq_level)
@@ -266,5 +268,7 @@
#define KVM_SET_FPU _IOW(KVMIO, 0x8d, struct kvm_fpu)
#define KVM_GET_LAPIC _IOR(KVMIO, 0x8e, struct kvm_lapic_state)
#define KVM_SET_LAPIC _IOW(KVMIO, 0x8f, struct kvm_lapic_state)
+#define KVM_SET_CPUID2 _IOW(KVMIO, 0x90, struct kvm_cpuid2)
+#define KVM_GET_CPUID2 _IOWR(KVMIO, 0x91, struct kvm_cpuid2)
#endif