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Subject[PATCH 37/39] KVM: Add HYPER-V apic access MSRs
Date
From: Gleb Natapov <gleb@redhat.com>

Implement HYPER-V apic MSRs. Spec defines three MSRs that speed-up
access to EOI/TPR/ICR apic registers for PV guests.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Vadim Rozenfeld <vrozenfe@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
---
arch/x86/include/asm/kvm_host.h | 2 +
arch/x86/kvm/lapic.c | 31 ++++++++++++++++++++++++++++
arch/x86/kvm/lapic.h | 8 +++++++
arch/x86/kvm/x86.c | 42 +++++++++++++++++++++++++++++++++++---
include/linux/kvm.h | 1 +
5 files changed, 80 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 67d19e4..a1f0b5d 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -363,6 +363,8 @@ struct kvm_vcpu_arch {
/* used for guest single stepping over the given code position */
u16 singlestep_cs;
unsigned long singlestep_rip;
+ /* fields used by HYPER-V emulation */
+ u64 hv_vapic;
};

struct kvm_mem_alias {
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index ba8c045..4b224f9 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1246,3 +1246,34 @@ int kvm_x2apic_msr_read(struct kvm_vcpu *vcpu, u32 msr, u64 *data)

return 0;
}
+
+int kvm_hv_vapic_msr_write(struct kvm_vcpu *vcpu, u32 reg, u64 data)
+{
+ struct kvm_lapic *apic = vcpu->arch.apic;
+
+ if (!irqchip_in_kernel(vcpu->kvm))
+ return 1;
+
+ /* if this is ICR write vector before command */
+ if (reg == APIC_ICR)
+ apic_reg_write(apic, APIC_ICR2, (u32)(data >> 32));
+ return apic_reg_write(apic, reg, (u32)data);
+}
+
+int kvm_hv_vapic_msr_read(struct kvm_vcpu *vcpu, u32 reg, u64 *data)
+{
+ struct kvm_lapic *apic = vcpu->arch.apic;
+ u32 low, high = 0;
+
+ if (!irqchip_in_kernel(vcpu->kvm))
+ return 1;
+
+ if (apic_reg_read(apic, reg, 4, &low))
+ return 1;
+ if (reg == APIC_ICR)
+ apic_reg_read(apic, APIC_ICR2, 4, &high);
+
+ *data = (((u64)high) << 32) | low;
+
+ return 0;
+}
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index 40010b0..f5fe32c 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -48,4 +48,12 @@ void kvm_lapic_sync_to_vapic(struct kvm_vcpu *vcpu);

int kvm_x2apic_msr_write(struct kvm_vcpu *vcpu, u32 msr, u64 data);
int kvm_x2apic_msr_read(struct kvm_vcpu *vcpu, u32 msr, u64 *data);
+
+int kvm_hv_vapic_msr_write(struct kvm_vcpu *vcpu, u32 msr, u64 data);
+int kvm_hv_vapic_msr_read(struct kvm_vcpu *vcpu, u32 msr, u64 *data);
+
+static inline bool kvm_hv_vapic_assist_page_enabled(struct kvm_vcpu *vcpu)
+{
+ return vcpu->arch.hv_vapic & HV_X64_MSR_APIC_ASSIST_PAGE_ENABLE;
+}
#endif
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 480137d..552be51 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -622,10 +622,11 @@ static inline u32 bit(int bitno)
* kvm-specific. Those are put in the beginning of the list.
*/

-#define KVM_SAVE_MSRS_BEGIN 4
+#define KVM_SAVE_MSRS_BEGIN 5
static u32 msrs_to_save[] = {
MSR_KVM_SYSTEM_TIME, MSR_KVM_WALL_CLOCK,
HV_X64_MSR_GUEST_OS_ID, HV_X64_MSR_HYPERCALL,
+ HV_X64_MSR_APIC_ASSIST_PAGE,
MSR_IA32_SYSENTER_CS, MSR_IA32_SYSENTER_ESP, MSR_IA32_SYSENTER_EIP,
MSR_K6_STAR,
#ifdef CONFIG_X86_64
@@ -1067,10 +1068,36 @@ static int set_msr_hyperv_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data)

static int set_msr_hyperv(struct kvm_vcpu *vcpu, u32 msr, u64 data)
{
- pr_unimpl(vcpu, "HYPER-V unimplemented wrmsr: 0x%x data 0x%llx\n",
- msr, data);
+ switch (msr) {
+ case HV_X64_MSR_APIC_ASSIST_PAGE: {
+ unsigned long addr;

- return 1;
+ if (!(data & HV_X64_MSR_APIC_ASSIST_PAGE_ENABLE)) {
+ vcpu->arch.hv_vapic = data;
+ break;
+ }
+ addr = gfn_to_hva(vcpu->kvm, data >>
+ HV_X64_MSR_APIC_ASSIST_PAGE_ADDRESS_SHIFT);
+ if (kvm_is_error_hva(addr))
+ return 1;
+ if (clear_user((void __user *)addr, PAGE_SIZE))
+ return 1;
+ vcpu->arch.hv_vapic = data;
+ break;
+ }
+ case HV_X64_MSR_EOI:
+ return kvm_hv_vapic_msr_write(vcpu, APIC_EOI, data);
+ case HV_X64_MSR_ICR:
+ return kvm_hv_vapic_msr_write(vcpu, APIC_ICR, data);
+ case HV_X64_MSR_TPR:
+ return kvm_hv_vapic_msr_write(vcpu, APIC_TASKPRI, data);
+ default:
+ pr_unimpl(vcpu, "HYPER-V unimplemented wrmsr: 0x%x "
+ "data 0x%llx\n", msr, data);
+ return 1;
+ }
+
+ return 0;
}

int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
@@ -1330,6 +1357,12 @@ static int get_msr_hyperv(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
data = r;
break;
}
+ case HV_X64_MSR_EOI:
+ return kvm_hv_vapic_msr_read(vcpu, APIC_EOI, pdata);
+ case HV_X64_MSR_ICR:
+ return kvm_hv_vapic_msr_read(vcpu, APIC_ICR, pdata);
+ case HV_X64_MSR_TPR:
+ return kvm_hv_vapic_msr_read(vcpu, APIC_TASKPRI, pdata);
default:
pr_unimpl(vcpu, "Hyper-V unhandled rdmsr: 0x%x\n", msr);
return 1;
@@ -1530,6 +1563,7 @@ int kvm_dev_ioctl_check_extension(long ext)
case KVM_CAP_ADJUST_CLOCK:
case KVM_CAP_VCPU_EVENTS:
case KVM_CAP_HYPERV:
+ case KVM_CAP_HYPERV_VAPIC:
r = 1;
break;
case KVM_CAP_COALESCED_MMIO:
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index e227cba..5ce6173 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -498,6 +498,7 @@ struct kvm_ioeventfd {
#define KVM_CAP_S390_PSW 42
#define KVM_CAP_PPC_SEGSTATE 43
#define KVM_CAP_HYPERV 44
+#define KVM_CAP_HYPERV_VAPIC 45

#ifdef KVM_CAP_IRQ_ROUTING

--
1.6.5.3


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