[RFC PATCH 06/14] RISC-V: KVM: Add steal-update vcpu request

[Andrew Jones]

Add a new vcpu request to inform a vcpu that it should record its
steal-time information. The request is made each time it has been
detected that the vcpu task was not assigned a cpu for some time,
which is easy to do by making the request from vcpu-load. The record
function is just a stub for now and will be filled in with the rest
of the steal-time support functions in following patches.

Signed-off-by: Andrew Jones <ajones at ventanamicro.com>
---
 arch/riscv/include/asm/kvm_host.h | 3 +++
 arch/riscv/kvm/vcpu.c             | 5 +++++
 arch/riscv/kvm/vcpu_sbi_sta.c     | 4 ++++
 3 files changed, 12 insertions(+)

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index cc7da66ee0c0..d6c78750f7f2 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -37,6 +37,7 @@
 	KVM_ARCH_REQ_FLAGS(4, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
 #define KVM_REQ_HFENCE			\
 	KVM_ARCH_REQ_FLAGS(5, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
+#define KVM_REQ_STEAL_UPDATE		KVM_ARCH_REQ(6)
 
 enum kvm_riscv_hfence_type {
 	KVM_RISCV_HFENCE_UNKNOWN = 0,
@@ -331,4 +332,6 @@ bool kvm_riscv_vcpu_has_interrupts(struct kvm_vcpu *vcpu, unsigned long mask);
 void kvm_riscv_vcpu_power_off(struct kvm_vcpu *vcpu);
 void kvm_riscv_vcpu_power_on(struct kvm_vcpu *vcpu);
 
+void kvm_riscv_vcpu_record_steal_time(struct kvm_vcpu *vcpu);
+
 #endif /* __RISCV_KVM_HOST_H__ */
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 02b49cb94561..733d87a13d42 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -901,6 +901,8 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	kvm_riscv_vcpu_guest_fp_restore(&vcpu->arch.guest_context,
 					vcpu->arch.isa);
 
+	kvm_make_request(KVM_REQ_STEAL_UPDATE, vcpu);
+
 	vcpu->cpu = cpu;
 }
 
@@ -969,6 +971,9 @@ static void kvm_riscv_check_vcpu_requests(struct kvm_vcpu *vcpu)
 
 		if (kvm_check_request(KVM_REQ_HFENCE, vcpu))
 			kvm_riscv_hfence_process(vcpu);
+
+		if (kvm_check_request(KVM_REQ_STEAL_UPDATE, vcpu))
+			kvm_riscv_vcpu_record_steal_time(vcpu);
 	}
 }
 
diff --git a/arch/riscv/kvm/vcpu_sbi_sta.c b/arch/riscv/kvm/vcpu_sbi_sta.c
index de9ad7b7d010..40de9cc13cbf 100644
--- a/arch/riscv/kvm/vcpu_sbi_sta.c
+++ b/arch/riscv/kvm/vcpu_sbi_sta.c
@@ -8,6 +8,10 @@
 #include <asm/kvm_vcpu_sbi.h>
 #include <asm/sbi.h>
 
+void kvm_riscv_vcpu_record_steal_time(struct kvm_vcpu *vcpu)
+{
+}
+
 static int kvm_sbi_sta_set_steal_time_shmem(struct kvm_vcpu *vcpu)
 {
 	return SBI_ERR_FAILURE;
-- 
2.39.2