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KVM: Activate Virtualization On Demand

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X86 CPUs need to have some magic happening to enable the virtualization
extensions on them. This magic can result in unpleasant results for
users, like blocking other VMMs from working (vmx) or using invalid TLB
entries (svm).

Currently KVM activates virtualization when the respective kernel module
is loaded. This blocks us from autoloading KVM modules without breaking
other VMMs.

To circumvent this problem at least a bit, this patch introduces on
demand activation of virtualization. This means, that instead
virtualization is enabled on creation of the first virtual machine
and disabled on destruction of the last one.

So using this, KVM can be easily autoloaded, while keeping other
hypervisors usable.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Alexander Graf
2009-09-15 11:37:46 +02:00
committed by Avi Kivity
parent e8b3433a5c
commit 10474ae894
9 changed files with 108 additions and 28 deletions
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arch/x86/kvm/svm.c
+9 -4
View File
@@ -316,7 +316,7 @@ static void svm_hardware_disable(void *garbage)
cpu_svm_disable();
}
static void svm_hardware_enable(void *garbage)
static int svm_hardware_enable(void *garbage)
{
struct svm_cpu_data *svm_data;
@@ -325,16 +325,20 @@ static void svm_hardware_enable(void *garbage)
struct desc_struct *gdt;
int me = raw_smp_processor_id();
rdmsrl(MSR_EFER, efer);
if (efer & EFER_SVME)
return -EBUSY;
if (!has_svm()) {
printk(KERN_ERR "svm_cpu_init: err EOPNOTSUPP on %d\n", me);
return;
return -EINVAL;
}
svm_data = per_cpu(svm_data, me);
if (!svm_data) {
printk(KERN_ERR "svm_cpu_init: svm_data is NULL on %d\n",
me);
return;
return -EINVAL;
}
svm_data->asid_generation = 1;
@@ -345,11 +349,12 @@ static void svm_hardware_enable(void *garbage)
gdt = (struct desc_struct *)gdt_descr.base;
svm_data->tss_desc = (struct kvm_ldttss_desc *)(gdt + GDT_ENTRY_TSS);
rdmsrl(MSR_EFER, efer);
wrmsrl(MSR_EFER, efer | EFER_SVME);
wrmsrl(MSR_VM_HSAVE_PA,
page_to_pfn(svm_data->save_area) << PAGE_SHIFT);
return 0;
}
static void svm_cpu_uninit(int cpu)