Newer userspace may run on an older kernel. Therefore we need a way to
check the capabilities of the kernel so that we can downgrade userspace
dynamically if necessary
Signed-off-by: Gregory Haskins <[EMAIL PROTECTED]>
---
qemu/qemu-kvm.c | 19 +++++++++++++++++++
user/kvmctl.c | 14 ++++++++++++++
user/kvmctl.h | 5 +++++
3 files changed, 38 insertions(+), 0 deletions(-)
diff --git a/qemu/qemu-kvm.c b/qemu/qemu-kvm.c
index 59e79bf..6096f21 100644
--- a/qemu/qemu-kvm.c
+++ b/qemu/qemu-kvm.c
@@ -697,6 +697,25 @@ int kvm_qemu_init()
int kvm_qemu_create_context(void)
{
int i;
+ uint64_t ext;
+
+ if (kvm_check_extension(kvm_context, &ext) < 0) {
+ kvm_qemu_destroy();
+ return -1;
+ }
+
+ if (!(ext & KVM_EXTENSION_LAPIC) && kvm_apic_level) {
+ /*
+ * Opps... the kernel doesnt support apic-emulation even though
+ * the user wants it. We must turn this off and warn the user
+ */
+ kvm_apic_level = 0;
+
+ /* FIXME: We should log this officially */
+ printf("WARNING: older kernel does not support apic " \
+ "emulation. Falling back to userspace emulation. Upgrade " \
+ "your kernel/modules\n");
+ }
if (kvm_create(kvm_context, phys_ram_size, kvm_apic_level,
(void**)&phys_ram_base) < 0) {
diff --git a/user/kvmctl.c b/user/kvmctl.c
index ea86426..fcabc1a 100644
--- a/user/kvmctl.c
+++ b/user/kvmctl.c
@@ -889,3 +889,17 @@ int kvm_set_signal_mask(kvm_context_t kvm, int vcpu, const
sigset_t *sigset)
free(sigmask);
return r;
}
+
+int kvm_check_extension(kvm_context_t kvm, uint64_t *ext)
+{
+ *ext = 0;
+
+ int r = ioctl(kvm->fd, KVM_CHECK_EXTENSION, KVM_APIC_MSG);
+ if (r < 0)
+ return r;
+
+ if (r)
+ *ext |= KVM_EXTENSION_LAPIC;
+
+ return 0;
+}
diff --git a/user/kvmctl.h b/user/kvmctl.h
index 07cbc08..5371d71 100644
--- a/user/kvmctl.h
+++ b/user/kvmctl.h
@@ -384,4 +384,9 @@ int kvm_dirty_pages_log_enable_all(kvm_context_t kvm);
*/
int kvm_dirty_pages_log_reset(kvm_context_t kvm);
+#define KVM_EXTENSION_LAPIC (1<<0)
+
+int kvm_check_extension(kvm_context_t kvm, uint64_t *ext);
+
+
#endif
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