RISC-V: KVM: Add remote HFENCE functions based on VCPU requests

The generic KVM has support for VCPU requests which can be used
to do arch-specific work in the run-loop. We introduce remote
HFENCE functions which will internally use VCPU requests instead
of host SBI calls.

Advantages of doing remote HFENCEs as VCPU requests are:
1) Multiple VCPUs of a Guest may be running on different Host CPUs
   so it is not always possible to determine the Host CPU mask for
   doing Host SBI call. For example, when VCPU X wants to do HFENCE
   on VCPU Y, it is possible that VCPU Y is blocked or in user-space
   (i.e. vcpu->cpu < 0).
2) To support nested virtualization, we will be having a separate
   shadow G-stage for each VCPU and a common host G-stage for the
   entire Guest/VM. The VCPU requests based remote HFENCEs helps
   us easily synchronize the common host G-stage and shadow G-stage
   of each VCPU without any additional IPI calls.

This is also a preparatory patch for upcoming nested virtualization
support where we will be having a shadow G-stage page table for
each Guest VCPU.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>

1 files changed, 59 insertions, 0 deletions

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index 0a804021db8c..01915d5f0094 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -12,6 +12,7 @@
 #include <linux/types.h>
 #include <linux/kvm.h>
 #include <linux/kvm_types.h>
+#include <linux/spinlock.h>
 #include <asm/csr.h>
 #include <asm/kvm_vcpu_fp.h>
 #include <asm/kvm_vcpu_timer.h>
@@ -26,6 +27,31 @@
 	KVM_ARCH_REQ_FLAGS(0, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
 #define KVM_REQ_VCPU_RESET		KVM_ARCH_REQ(1)
 #define KVM_REQ_UPDATE_HGATP		KVM_ARCH_REQ(2)
+#define KVM_REQ_FENCE_I			\
+	KVM_ARCH_REQ_FLAGS(3, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
+#define KVM_REQ_HFENCE_GVMA_VMID_ALL	KVM_REQ_TLB_FLUSH
+#define KVM_REQ_HFENCE_VVMA_ALL		\
+	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)
+
+enum kvm_riscv_hfence_type {
+	KVM_RISCV_HFENCE_UNKNOWN = 0,
+	KVM_RISCV_HFENCE_GVMA_VMID_GPA,
+	KVM_RISCV_HFENCE_VVMA_ASID_GVA,
+	KVM_RISCV_HFENCE_VVMA_ASID_ALL,
+	KVM_RISCV_HFENCE_VVMA_GVA,
+};
+
+struct kvm_riscv_hfence {
+	enum kvm_riscv_hfence_type type;
+	unsigned long asid;
+	unsigned long order;
+	gpa_t addr;
+	gpa_t size;
+};
+
+#define KVM_RISCV_VCPU_MAX_HFENCE	64
 
 struct kvm_vm_stat {
 	struct kvm_vm_stat_generic generic;
@@ -178,6 +204,12 @@ struct kvm_vcpu_arch {
 	/* VCPU Timer */
 	struct kvm_vcpu_timer timer;
 
+	/* HFENCE request queue */
+	spinlock_t hfence_lock;
+	unsigned long hfence_head;
+	unsigned long hfence_tail;
+	struct kvm_riscv_hfence hfence_queue[KVM_RISCV_VCPU_MAX_HFENCE];
+
 	/* MMIO instruction details */
 	struct kvm_mmio_decode mmio_decode;
 
@@ -221,6 +253,33 @@ void kvm_riscv_local_hfence_vvma_gva(unsigned long vmid,
 				     unsigned long order);
 void kvm_riscv_local_hfence_vvma_all(unsigned long vmid);
 
+void kvm_riscv_fence_i_process(struct kvm_vcpu *vcpu);
+void kvm_riscv_hfence_gvma_vmid_all_process(struct kvm_vcpu *vcpu);
+void kvm_riscv_hfence_vvma_all_process(struct kvm_vcpu *vcpu);
+void kvm_riscv_hfence_process(struct kvm_vcpu *vcpu);
+
+void kvm_riscv_fence_i(struct kvm *kvm,
+		       unsigned long hbase, unsigned long hmask);
+void kvm_riscv_hfence_gvma_vmid_gpa(struct kvm *kvm,
+				    unsigned long hbase, unsigned long hmask,
+				    gpa_t gpa, gpa_t gpsz,
+				    unsigned long order);
+void kvm_riscv_hfence_gvma_vmid_all(struct kvm *kvm,
+				    unsigned long hbase, unsigned long hmask);
+void kvm_riscv_hfence_vvma_asid_gva(struct kvm *kvm,
+				    unsigned long hbase, unsigned long hmask,
+				    unsigned long gva, unsigned long gvsz,
+				    unsigned long order, unsigned long asid);
+void kvm_riscv_hfence_vvma_asid_all(struct kvm *kvm,
+				    unsigned long hbase, unsigned long hmask,
+				    unsigned long asid);
+void kvm_riscv_hfence_vvma_gva(struct kvm *kvm,
+			       unsigned long hbase, unsigned long hmask,
+			       unsigned long gva, unsigned long gvsz,
+			       unsigned long order);
+void kvm_riscv_hfence_vvma_all(struct kvm *kvm,
+			       unsigned long hbase, unsigned long hmask);
+
 int kvm_riscv_gstage_map(struct kvm_vcpu *vcpu,
 			 struct kvm_memory_slot *memslot,
 			 gpa_t gpa, unsigned long hva, bool is_write);