KVM: Add PV MSR to enable asynchronous page faults delivery.
Guest enables async PF vcpu functionality using this MSR.
Reviewed-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index c3076bc..0d70398 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -419,6 +419,8 @@
struct {
bool halted;
gfn_t gfns[roundup_pow_of_two(ASYNC_PF_PER_VCPU)];
+ struct gfn_to_hva_cache data;
+ u64 msr_val;
} apf;
};
diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
index e3faaaf..8662ae0 100644
--- a/arch/x86/include/asm/kvm_para.h
+++ b/arch/x86/include/asm/kvm_para.h
@@ -20,6 +20,7 @@
* are available. The use of 0x11 and 0x12 is deprecated
*/
#define KVM_FEATURE_CLOCKSOURCE2 3
+#define KVM_FEATURE_ASYNC_PF 4
/* The last 8 bits are used to indicate how to interpret the flags field
* in pvclock structure. If no bits are set, all flags are ignored.
@@ -32,9 +33,12 @@
/* Custom MSRs falls in the range 0x4b564d00-0x4b564dff */
#define MSR_KVM_WALL_CLOCK_NEW 0x4b564d00
#define MSR_KVM_SYSTEM_TIME_NEW 0x4b564d01
+#define MSR_KVM_ASYNC_PF_EN 0x4b564d02
#define KVM_MAX_MMU_OP_BATCH 32
+#define KVM_ASYNC_PF_ENABLED (1 << 0)
+
/* Operations for KVM_HC_MMU_OP */
#define KVM_MMU_OP_WRITE_PTE 1
#define KVM_MMU_OP_FLUSH_TLB 2
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index bd25477..063c072 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -783,12 +783,12 @@
* kvm-specific. Those are put in the beginning of the list.
*/
-#define KVM_SAVE_MSRS_BEGIN 7
+#define KVM_SAVE_MSRS_BEGIN 8
static u32 msrs_to_save[] = {
MSR_KVM_SYSTEM_TIME, MSR_KVM_WALL_CLOCK,
MSR_KVM_SYSTEM_TIME_NEW, MSR_KVM_WALL_CLOCK_NEW,
HV_X64_MSR_GUEST_OS_ID, HV_X64_MSR_HYPERCALL,
- HV_X64_MSR_APIC_ASSIST_PAGE,
+ HV_X64_MSR_APIC_ASSIST_PAGE, MSR_KVM_ASYNC_PF_EN,
MSR_IA32_SYSENTER_CS, MSR_IA32_SYSENTER_ESP, MSR_IA32_SYSENTER_EIP,
MSR_STAR,
#ifdef CONFIG_X86_64
@@ -1425,6 +1425,29 @@
return 0;
}
+static int kvm_pv_enable_async_pf(struct kvm_vcpu *vcpu, u64 data)
+{
+ gpa_t gpa = data & ~0x3f;
+
+ /* Bits 1:5 are resrved, Should be zero */
+ if (data & 0x3e)
+ return 1;
+
+ vcpu->arch.apf.msr_val = data;
+
+ if (!(data & KVM_ASYNC_PF_ENABLED)) {
+ kvm_clear_async_pf_completion_queue(vcpu);
+ kvm_async_pf_hash_reset(vcpu);
+ return 0;
+ }
+
+ if (kvm_gfn_to_hva_cache_init(vcpu->kvm, &vcpu->arch.apf.data, gpa))
+ return 1;
+
+ kvm_async_pf_wakeup_all(vcpu);
+ return 0;
+}
+
int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
{
switch (msr) {
@@ -1506,6 +1529,10 @@
}
break;
}
+ case MSR_KVM_ASYNC_PF_EN:
+ if (kvm_pv_enable_async_pf(vcpu, data))
+ return 1;
+ break;
case MSR_IA32_MCG_CTL:
case MSR_IA32_MCG_STATUS:
case MSR_IA32_MC0_CTL ... MSR_IA32_MC0_CTL + 4 * KVM_MAX_MCE_BANKS - 1:
@@ -1782,6 +1809,9 @@
case MSR_KVM_SYSTEM_TIME_NEW:
data = vcpu->arch.time;
break;
+ case MSR_KVM_ASYNC_PF_EN:
+ data = vcpu->arch.apf.msr_val;
+ break;
case MSR_IA32_P5_MC_ADDR:
case MSR_IA32_P5_MC_TYPE:
case MSR_IA32_MCG_CAP:
@@ -1929,6 +1959,7 @@
case KVM_CAP_DEBUGREGS:
case KVM_CAP_X86_ROBUST_SINGLESTEP:
case KVM_CAP_XSAVE:
+ case KVM_CAP_ASYNC_PF:
r = 1;
break;
case KVM_CAP_COALESCED_MMIO:
@@ -5792,6 +5823,8 @@
void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
{
+ vcpu->arch.apf.msr_val = 0;
+
vcpu_load(vcpu);
kvm_mmu_unload(vcpu);
vcpu_put(vcpu);
@@ -5811,6 +5844,7 @@
vcpu->arch.dr7 = DR7_FIXED_1;
kvm_make_request(KVM_REQ_EVENT, vcpu);
+ vcpu->arch.apf.msr_val = 0;
kvm_clear_async_pf_completion_queue(vcpu);
kvm_async_pf_hash_reset(vcpu);