LoongArch: KVM: Add hypercall service support for usermode VMM

Some VMMs provides special hypercall service in usermode, KVM should not
handle the usermode hypercall service, thus pass it to usermode, let the
usermode VMM handle it.

Here a new code KVM_HCALL_CODE_USER_SERVICE is added for the user-mode
hypercall service, KVM lets all six registers visible to usermode VMM.

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

diff --git a/arch/loongarch/include/asm/kvm_host.h b/arch/loongarch/include/asm/kvm_host.h
index 7b8367c39da85f2328663d44f6cf82457dca7290..590982cd986ec8186ade85df96e252570d2ec444 100644 (file)
--- a/arch/loongarch/include/asm/kvm_host.h
+++ b/arch/loongarch/include/asm/kvm_host.h
@@ -162,6 +162,7 @@ enum emulation_result {
 #define LOONGARCH_PV_FEAT_UPDATED      BIT_ULL(63)
 #define LOONGARCH_PV_FEAT_MASK         (BIT(KVM_FEATURE_IPI) |         \
                                         BIT(KVM_FEATURE_STEAL_TIME) |  \
+                                        BIT(KVM_FEATURE_USER_HCALL) |  \
                                         BIT(KVM_FEATURE_VIRT_EXTIOI))
 
 struct kvm_vcpu_arch {

diff --git a/arch/loongarch/include/asm/kvm_para.h b/arch/loongarch/include/asm/kvm_para.h
index c4e84227280dc1ec74a362723972cb3de6830092..3e4b397f423f48f3157bf0efd1bd9d20bbd9d8e1 100644 (file)
--- a/arch/loongarch/include/asm/kvm_para.h
+++ b/arch/loongarch/include/asm/kvm_para.h
@@ -13,6 +13,7 @@
 
 #define KVM_HCALL_CODE_SERVICE         0
 #define KVM_HCALL_CODE_SWDBG           1
+#define KVM_HCALL_CODE_USER_SERVICE    2
 
 #define KVM_HCALL_SERVICE              HYPERCALL_ENCODE(HYPERVISOR_KVM, KVM_HCALL_CODE_SERVICE)
 #define  KVM_HCALL_FUNC_IPI            1
@@ -20,6 +21,8 @@
 
 #define KVM_HCALL_SWDBG                        HYPERCALL_ENCODE(HYPERVISOR_KVM, KVM_HCALL_CODE_SWDBG)
 
+#define KVM_HCALL_USER_SERVICE         HYPERCALL_ENCODE(HYPERVISOR_KVM, KVM_HCALL_CODE_USER_SERVICE)
+
 /*
  * LoongArch hypercall return code
  */

diff --git a/arch/loongarch/include/asm/kvm_vcpu.h b/arch/loongarch/include/asm/kvm_vcpu.h
index d7e8f7d50ee0ce13360336f6c66ba24c746989ea..2c349f961bfbcf5b2ed5983bc6c272b37957aa2b 100644 (file)
--- a/arch/loongarch/include/asm/kvm_vcpu.h
+++ b/arch/loongarch/include/asm/kvm_vcpu.h
@@ -43,6 +43,7 @@ int  kvm_emu_mmio_read(struct kvm_vcpu *vcpu, larch_inst inst);
 int  kvm_emu_mmio_write(struct kvm_vcpu *vcpu, larch_inst inst);
 int  kvm_complete_mmio_read(struct kvm_vcpu *vcpu, struct kvm_run *run);
 int  kvm_complete_iocsr_read(struct kvm_vcpu *vcpu, struct kvm_run *run);
+int  kvm_complete_user_service(struct kvm_vcpu *vcpu, struct kvm_run *run);
 int  kvm_emu_idle(struct kvm_vcpu *vcpu);
 int  kvm_pending_timer(struct kvm_vcpu *vcpu);
 int  kvm_handle_fault(struct kvm_vcpu *vcpu, int fault);

diff --git a/arch/loongarch/include/uapi/asm/kvm_para.h b/arch/loongarch/include/uapi/asm/kvm_para.h
index b0604aa9b4bbd29dfafedbdf59f571bd445c2c2c..76d802ef01ce3cb426fb8627a7aac7fb41cc6ec6 100644 (file)
--- a/arch/loongarch/include/uapi/asm/kvm_para.h
+++ b/arch/loongarch/include/uapi/asm/kvm_para.h
@@ -17,5 +17,6 @@
 #define  KVM_FEATURE_STEAL_TIME                2
 /* BIT 24 - 31 are features configurable by user space vmm */
 #define  KVM_FEATURE_VIRT_EXTIOI       24
+#define  KVM_FEATURE_USER_HCALL                25
 
 #endif /* _UAPI_ASM_KVM_PARA_H */

diff --git a/arch/loongarch/kvm/exit.c b/arch/loongarch/kvm/exit.c
index a7893bd01e732a85e116762eb10e18edd806450c..c1e8ec5b941b22cc32c0ed63e63d4fb6963c9559 100644 (file)
--- a/arch/loongarch/kvm/exit.c
+++ b/arch/loongarch/kvm/exit.c
@@ -709,6 +709,14 @@ static int kvm_handle_write_fault(struct kvm_vcpu *vcpu)
        return kvm_handle_rdwr_fault(vcpu, true);
 }
 
+int kvm_complete_user_service(struct kvm_vcpu *vcpu, struct kvm_run *run)
+{
+       update_pc(&vcpu->arch);
+       kvm_write_reg(vcpu, LOONGARCH_GPR_A0, run->hypercall.ret);
+
+       return 0;
+}
+
 /**
  * kvm_handle_fpu_disabled() - Guest used fpu however it is disabled at host
  * @vcpu:      Virtual CPU context.
@@ -873,6 +881,28 @@ static int kvm_handle_hypercall(struct kvm_vcpu *vcpu)
                vcpu->stat.hypercall_exits++;
                kvm_handle_service(vcpu);
                break;
+       case KVM_HCALL_USER_SERVICE:
+               if (!kvm_guest_has_pv_feature(vcpu, KVM_FEATURE_USER_HCALL)) {
+                       kvm_write_reg(vcpu, LOONGARCH_GPR_A0, KVM_HCALL_INVALID_CODE);
+                       break;
+               }
+
+               vcpu->stat.hypercall_exits++;
+               vcpu->run->exit_reason = KVM_EXIT_HYPERCALL;
+               vcpu->run->hypercall.nr = KVM_HCALL_USER_SERVICE;
+               vcpu->run->hypercall.args[0] = kvm_read_reg(vcpu, LOONGARCH_GPR_A0);
+               vcpu->run->hypercall.args[1] = kvm_read_reg(vcpu, LOONGARCH_GPR_A1);
+               vcpu->run->hypercall.args[2] = kvm_read_reg(vcpu, LOONGARCH_GPR_A2);
+               vcpu->run->hypercall.args[3] = kvm_read_reg(vcpu, LOONGARCH_GPR_A3);
+               vcpu->run->hypercall.args[4] = kvm_read_reg(vcpu, LOONGARCH_GPR_A4);
+               vcpu->run->hypercall.args[5] = kvm_read_reg(vcpu, LOONGARCH_GPR_A5);
+               vcpu->run->hypercall.flags = 0;
+               /*
+                * Set invalid return value by default, let user-mode VMM modify it.
+                */
+               vcpu->run->hypercall.ret = KVM_HCALL_INVALID_CODE;
+               ret = RESUME_HOST;
+               break;
        case KVM_HCALL_SWDBG:
                /* KVM_HCALL_SWDBG only in effective when SW_BP is enabled */
                if (vcpu->guest_debug & KVM_GUESTDBG_SW_BP_MASK) {

diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c
index d18a4a2704150ebdac537fe6348f1c6ae4daaca7..fb72095c8077e8c5b81db7c284f365e426483fd2 100644 (file)
--- a/arch/loongarch/kvm/vcpu.c
+++ b/arch/loongarch/kvm/vcpu.c
@@ -1732,9 +1732,14 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
                vcpu->mmio_needed = 0;
        }
 
-       if (run->exit_reason == KVM_EXIT_LOONGARCH_IOCSR) {
+       switch (run->exit_reason) {
+       case KVM_EXIT_HYPERCALL:
+               kvm_complete_user_service(vcpu, run);
+               break;
+       case KVM_EXIT_LOONGARCH_IOCSR:
                if (!run->iocsr_io.is_write)
                        kvm_complete_iocsr_read(vcpu, run);
+               break;
        }
 
        if (!vcpu->wants_to_run)