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Subject[PATCH v3 11/12] Let host know whether the guest can handle async PF in non-userspace context.
Date
If guest can detect that it runs in non-preemptable context it can
handle async PFs at any time, so let host know that it can send async
PF even if guest cpu is not in userspace.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/include/asm/kvm_para.h | 1 +
arch/x86/kernel/kvm.c | 3 +++
arch/x86/kvm/x86.c | 5 +++--
4 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 43c1aca..cb0fd75 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -365,6 +365,7 @@ struct kvm_vcpu_arch {
unsigned long singlestep_rip;

u32 __user *apf_data;
+ bool apf_send_user_only;
u32 apf_memslot_ver;
u64 apf_msr_val;
u32 async_pf_id;
diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
index 98edaa9..8a18560 100644
--- a/arch/x86/include/asm/kvm_para.h
+++ b/arch/x86/include/asm/kvm_para.h
@@ -24,6 +24,7 @@
#define KVM_MAX_MMU_OP_BATCH 32

#define KVM_ASYNC_PF_ENABLED (1 << 0)
+#define KVM_ASYNC_PF_SEND_ALWAYS (1 << 1)

/* Operations for KVM_HC_MMU_OP */
#define KVM_MMU_OP_WRITE_PTE 1
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 49549fd..4241706 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -480,6 +480,9 @@ void __cpuinit kvm_guest_cpu_init(void)
if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF)) {
u64 pa = __pa(&__get_cpu_var(apf_reason));

+#ifdef CONFIG_PREEMPT
+ pa |= KVM_ASYNC_PF_SEND_ALWAYS;
+#endif
if (native_write_msr_safe(MSR_KVM_ASYNC_PF_EN,
pa | KVM_ASYNC_PF_ENABLED, pa >> 32))
return;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e2e33ac..47f1661 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1009,8 +1009,8 @@ static int kvm_pv_enable_async_pf(struct kvm_vcpu *vcpu, u64 data)
int offset = offset_in_page(gpa);
unsigned long addr;

- /* Bits 1:5 are resrved, Should be zero */
- if (data & 0x3e)
+ /* Bits 2:5 are resrved, Should be zero */
+ if (data & 0x3c)
return 1;

vcpu->arch.apf_msr_val = data;
@@ -1032,6 +1032,7 @@ static int kvm_pv_enable_async_pf(struct kvm_vcpu *vcpu, u64 data)
return 1;
}
vcpu->arch.apf_memslot_ver = vcpu->kvm->memslot_version;
+ vcpu->arch.apf_send_user_only = !(data & KVM_ASYNC_PF_SEND_ALWAYS);
kvm_async_pf_wakeup_all(vcpu);
return 0;
}
--
1.6.5


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