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From:   Tianrui Zhao <zhaotianrui@loongson.cn>
To:     linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc:     Paolo Bonzini <pbonzini@redhat.com>,
        Huacai Chen <chenhuacai@kernel.org>,
        WANG Xuerui <kernel@xen0n.name>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        loongarch@lists.linux.dev, Jens Axboe <axboe@kernel.dk>,
        Mark Brown <broonie@kernel.org>,
        Alex Deucher <alexander.deucher@amd.com>,
        Oliver Upton <oliver.upton@linux.dev>, maobibo@loongson.cn,
        Xi Ruoyao <xry111@xry111.site>, zhaotianrui@loongson.cn
Subject: [PATCH v21 22/29] LoongArch: KVM: Implement handle gspr exception
Date:   Fri, 15 Sep 2023 09:49:42 +0800
Message-Id: <20230915014949.1222777-23-zhaotianrui@loongson.cn>
In-Reply-To: <20230915014949.1222777-1-zhaotianrui@loongson.cn>
References: <20230915014949.1222777-1-zhaotianrui@loongson.cn>
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Implement kvm handle gspr exception interface, including emulate the
reading and writing of cpucfg, csr, iocsr resource.

Reviewed-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Tianrui Zhao <zhaotianrui@loongson.cn>
---
 arch/loongarch/kvm/exit.c | 112 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 112 insertions(+)

diff --git a/arch/loongarch/kvm/exit.c b/arch/loongarch/kvm/exit.c
index 9f3d9131c1..a86586cdfc 100644
--- a/arch/loongarch/kvm/exit.c
+++ b/arch/loongarch/kvm/exit.c
@@ -219,3 +219,115 @@ int kvm_emu_idle(struct kvm_vcpu *vcpu)
 
 	return EMULATE_DONE;
 }
+
+static int kvm_trap_handle_gspr(struct kvm_vcpu *vcpu)
+{
+	enum emulation_result er = EMULATE_DONE;
+	struct kvm_run *run = vcpu->run;
+	larch_inst inst;
+	unsigned long curr_pc;
+	int rd, rj;
+	unsigned int index;
+
+	/*
+	 *  Fetch the instruction.
+	 */
+	inst.word = vcpu->arch.badi;
+	curr_pc = vcpu->arch.pc;
+	update_pc(&vcpu->arch);
+
+	trace_kvm_exit_gspr(vcpu, inst.word);
+	er = EMULATE_FAIL;
+	switch (((inst.word >> 24) & 0xff)) {
+	case 0x0:
+		/* cpucfg GSPR */
+		if (inst.reg2_format.opcode == 0x1B) {
+			rd = inst.reg2_format.rd;
+			rj = inst.reg2_format.rj;
+			++vcpu->stat.cpucfg_exits;
+			index = vcpu->arch.gprs[rj];
+			er = EMULATE_DONE;
+			/*
+			 * By LoongArch Reference Manual 2.2.10.5
+			 * return value is 0 for undefined cpucfg index
+			 */
+			if (index < KVM_MAX_CPUCFG_REGS)
+				vcpu->arch.gprs[rd] = vcpu->arch.cpucfg[index];
+			else
+				vcpu->arch.gprs[rd] = 0;
+		}
+		break;
+	case 0x4:
+		/* csr GSPR */
+		er = kvm_handle_csr(vcpu, inst);
+		break;
+	case 0x6:
+		/* iocsr,cache,idle GSPR */
+		switch (((inst.word >> 22) & 0x3ff)) {
+		case 0x18:
+			/* cache GSPR */
+			er = EMULATE_DONE;
+			trace_kvm_exit_cache(vcpu, KVM_TRACE_EXIT_CACHE);
+			break;
+		case 0x19:
+			/* iocsr/idle GSPR */
+			switch (((inst.word >> 15) & 0x1ffff)) {
+			case 0xc90:
+				/* iocsr GSPR */
+				er = kvm_emu_iocsr(inst, run, vcpu);
+				break;
+			case 0xc91:
+				/* idle GSPR */
+				er = kvm_emu_idle(vcpu);
+				break;
+			default:
+				er = EMULATE_FAIL;
+				break;
+			}
+			break;
+		default:
+			er = EMULATE_FAIL;
+			break;
+		}
+		break;
+	default:
+		er = EMULATE_FAIL;
+		break;
+	}
+
+	/* Rollback PC only if emulation was unsuccessful */
+	if (er == EMULATE_FAIL) {
+		kvm_err("[%#lx]%s: unsupported gspr instruction 0x%08x\n",
+			curr_pc, __func__, inst.word);
+
+		kvm_arch_vcpu_dump_regs(vcpu);
+		vcpu->arch.pc = curr_pc;
+	}
+	return er;
+}
+
+/*
+ * Execute cpucfg instruction will tirggerGSPR,
+ * Also the access to unimplemented csrs 0x15
+ * 0x16, 0x50~0x53, 0x80, 0x81, 0x90~0x95, 0x98
+ * 0xc0~0xff, 0x100~0x109, 0x500~0x502,
+ * cache_op, idle_op iocsr ops the same
+ */
+static int kvm_handle_gspr(struct kvm_vcpu *vcpu)
+{
+	enum emulation_result er = EMULATE_DONE;
+	int ret = RESUME_GUEST;
+
+	er = kvm_trap_handle_gspr(vcpu);
+
+	if (er == EMULATE_DONE) {
+		ret = RESUME_GUEST;
+	} else if (er == EMULATE_DO_IOCSR) {
+		vcpu->run->exit_reason = KVM_EXIT_LOONGARCH_IOCSR;
+		ret = RESUME_HOST;
+	} else {
+		kvm_queue_exception(vcpu, EXCCODE_INE, 0);
+		ret = RESUME_GUEST;
+	}
+	return ret;
+}
-- 
2.39.1