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Message-Id: <20250103023053.2625226-1-maobibo@loongson.cn>
Date: Fri, 3 Jan 2025 10:30:53 +0800
From: Bibo Mao <maobibo@...ngson.cn>
To: Tianrui Zhao <zhaotianrui@...ngson.cn>,
Huacai Chen <chenhuacai@...nel.org>
Cc: WANG Xuerui <kernel@...0n.name>,
kvm@...r.kernel.org,
loongarch@...ts.linux.dev,
linux-kernel@...r.kernel.org
Subject: [PATCH v2] LoongArch: KVM: Add hypercall service support for usermode VMM
Some VMMs provides special hypercall service in usermode, KVM need
not handle the usermode hypercall service and pass it to VMM and
let VMM handle it.
Here new code KVM_HCALL_CODE_USER is added for user-mode hypercall
service, KVM lets all six registers visiable to VMM.
Signed-off-by: Bibo Mao <maobibo@...ngson.cn>
---
v1 ... v2:
1. Add function kvm_complete_user_service() when finish hypercall
in user-mode VMM and continue to run.
2. Add hypercall_exits stat information.
---
arch/loongarch/include/asm/kvm_host.h | 1 +
arch/loongarch/include/asm/kvm_para.h | 2 ++
arch/loongarch/include/asm/kvm_vcpu.h | 1 +
arch/loongarch/include/uapi/asm/kvm_para.h | 1 +
arch/loongarch/kvm/exit.c | 30 ++++++++++++++++++++++
arch/loongarch/kvm/vcpu.c | 3 ++-
6 files changed, 37 insertions(+), 1 deletion(-)
diff --git a/arch/loongarch/include/asm/kvm_host.h b/arch/loongarch/include/asm/kvm_host.h
index 7b8367c39da8..590982cd986e 100644
--- 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 c4e84227280d..d3c00de484f6 100644
--- a/arch/loongarch/include/asm/kvm_para.h
+++ b/arch/loongarch/include/asm/kvm_para.h
@@ -13,12 +13,14 @@
#define KVM_HCALL_CODE_SERVICE 0
#define KVM_HCALL_CODE_SWDBG 1
+#define KVM_HCALL_CODE_USER 2
#define KVM_HCALL_SERVICE HYPERCALL_ENCODE(HYPERVISOR_KVM, KVM_HCALL_CODE_SERVICE)
#define KVM_HCALL_FUNC_IPI 1
#define KVM_HCALL_FUNC_NOTIFY 2
#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)
/*
* LoongArch hypercall return code
diff --git a/arch/loongarch/include/asm/kvm_vcpu.h b/arch/loongarch/include/asm/kvm_vcpu.h
index d7e8f7d50ee0..2c349f961bfb 100644
--- 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 b0604aa9b4bb..76d802ef01ce 100644
--- 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 a7893bd01e73..70b5ed1241c4 100644
--- a/arch/loongarch/kvm/exit.c
+++ b/arch/loongarch/kvm/exit.c
@@ -538,6 +538,13 @@ int kvm_complete_mmio_read(struct kvm_vcpu *vcpu, struct kvm_run *run)
return er;
}
+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;
+}
+
int kvm_emu_mmio_write(struct kvm_vcpu *vcpu, larch_inst inst)
{
int idx, ret;
@@ -873,6 +880,29 @@ 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
+ * Need 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 d18a4a270415..888480a5bc25 100644
--- a/arch/loongarch/kvm/vcpu.c
+++ b/arch/loongarch/kvm/vcpu.c
@@ -1735,7 +1735,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
if (run->exit_reason == KVM_EXIT_LOONGARCH_IOCSR) {
if (!run->iocsr_io.is_write)
kvm_complete_iocsr_read(vcpu, run);
- }
+ } else if (run->exit_reason == KVM_EXIT_HYPERCALL)
+ kvm_complete_user_service(vcpu, run);
if (!vcpu->wants_to_run)
return r;
base-commit: fc033cf25e612e840e545f8d5ad2edd6ba613ed5
--
2.39.3
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