KVM: s390: arm64: Implement required functions

Implement the mostly trivial functions that the shared arm64 (kvm)
code & headers oblige s390 to implement.

MAINTAINERS: Add arch/s390/include/arm64/* to KVM/s390

Implement a very basic smccc handler that (non-compliantly) is just able
to stop a vcpu.

Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>

MAINTAINERS

@@ -14372,6 +14372,7 @@ L:	kvm@vger.kernel.org
 S:	Supported
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux.git
 F:	Documentation/virt/kvm/s390*
+F:	arch/s390/include/arm64/*
 F:	arch/s390/include/asm/gmap_helpers.h
 F:	arch/s390/include/asm/kvm*
 F:	arch/s390/include/uapi/asm/kvm*

arch/s390/include/arm64/kvm_emulate.h

@@ -0,0 +1,130 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __S390_ARM64_KVM_EMULATE_H__
+#define __S390_ARM64_KVM_EMULATE_H__
+
+#include <asm/fault.h>
+#include <linux/kvm_host.h>
+
+#include <arm64/kvm_nested.h>
+#include <arm64/ptrace.h>
+#include <arm64/kvm_arm.h>
+#include <arm64/sysreg.h>
+
+static __always_inline unsigned long *vcpu_pc(const struct kvm_vcpu *vcpu)
+{
+	return (unsigned long *)&vcpu->arch.sae_block.pc;
+}
+
+static __always_inline unsigned long *vcpu_cpsr(const struct kvm_vcpu *vcpu)
+{
+	return (unsigned long *)&vcpu->arch.sae_block.pstate;
+}
+
+static __always_inline unsigned long *vcpu_sp_el0(const struct kvm_vcpu *vcpu)
+{
+	return (unsigned long *)&vcpu->arch.sae_block.sp_el0;
+}
+
+static __always_inline u64 *vcpu_sp_el1(struct kvm_vcpu *vcpu)
+{
+	return &vcpu->arch.sae_block.sp_el1;
+}
+
+static __always_inline __vector128 *vcpu_vreg(struct kvm_vcpu *vcpu, int off)
+{
+	return &vcpu->arch.ctxt.vregs[off];
+}
+
+static __always_inline u32 *vcpu_fpsr(struct kvm_vcpu *vcpu)
+{
+	return &vcpu->arch.sae_block.fpsr;
+}
+
+static __always_inline u32 *vcpu_fpcr(struct kvm_vcpu *vcpu)
+{
+	return &vcpu->arch.sae_block.fpcr;
+}
+
+static __always_inline bool vcpu_mode_is_32bit(const struct kvm_vcpu *vcpu)
+{
+	return false;
+}
+
+static __always_inline u64 kvm_vcpu_get_esr(const struct kvm_vcpu *vcpu)
+{
+	return vcpu->arch.sae_block.hai.esr_el2;
+}
+
+static inline unsigned long *vcpu_hcr(struct kvm_vcpu *vcpu)
+{
+	return (unsigned long *)&vcpu->arch.hcr_el2;
+}
+
+static __always_inline unsigned long kvm_vcpu_get_hfar(const struct kvm_vcpu *vcpu)
+{
+	return vcpu->arch.sae_block.hai.far_el2;
+}
+
+static __always_inline phys_addr_t kvm_vcpu_get_fault_ipa(const struct kvm_vcpu *vcpu)
+{
+	return gfn_to_gpa(vcpu->arch.sae_block.hai.teid.addr);
+}
+
+static inline u16 kvm_vcpu_fault_pic(const struct kvm_vcpu *vcpu)
+{
+	return vcpu->arch.sae_block.hai.pic & PGM_INT_CODE_MASK;
+}
+
+static __always_inline
+bool kvm_vcpu_trap_is_permission_fault(const struct kvm_vcpu *vcpu)
+{
+	return kvm_vcpu_fault_pic(vcpu) == PGM_PROTECTION;
+}
+
+static __always_inline bool kvm_condition_valid(const struct kvm_vcpu *vcpu)
+{
+	return true;
+}
+
+static __always_inline bool vcpu_el1_is_32bit(struct kvm_vcpu *vcpu)
+{
+	return false;
+}
+
+static inline bool kvm_vcpu_is_be(struct kvm_vcpu *vcpu)
+{
+	return false;
+}
+
+static inline int kvm_vcpu_abt_gltl(struct kvm_vcpu *vcpu)
+{
+	return vcpu->arch.sae_block.hai.gltl;
+}
+
+static inline bool vcpu_mode_priv(const struct kvm_vcpu *vcpu)
+{
+	u32 mode = *vcpu_cpsr(vcpu) & PSR_MODE_MASK;
+
+	return mode != PSR_MODE_EL0t;
+}
+
+static inline void kvm_skip_instr(struct kvm_vcpu *vcpu)
+{
+	*vcpu_pc(vcpu) += 4;
+	*vcpu_cpsr(vcpu) &= ~PSR_BTYPE_MASK;
+
+	/* advance the singlestep state machine */
+	*vcpu_cpsr(vcpu) &= ~SPSR_ELx_SS;
+}
+
+static inline void kvm_reset_fpsimd(struct kvm_vcpu *vcpu)
+{
+	memset(vcpu->arch.ctxt.vregs, 0, sizeof(vcpu->arch.ctxt.vregs));
+	vcpu->arch.sae_block.fpsr = 0;
+	vcpu->arch.sae_block.fpcr = 0;
+}
+
+#include <arm64/kvm_emulate-gen.h>
+
+#endif /* __S390_ARM64_KVM_EMULATE_H__ */

arch/s390/include/arm64/kvm_nested.h

@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef ASM_KVM_NESTED_H
+#define ASM_KVM_NESTED_H
+
+static inline bool vcpu_has_nv(const struct kvm_vcpu *vcpu)
+{
+	return false;
+}
+
+#endif /* ASM_KVM_NESTED_H */

arch/s390/include/arm64/ptrace.h

@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __S390_ARM64_PTRACE_H__
+#define __S390_ARM64_PTRACE_H__
+
+#include <arm64/sysreg.h>
+#include <uapi/arm64/ptrace.h>
+
+#include <arm64/ptrace-gen.h>
+
+#endif /* __S390_ARM64_PTRACE_H__ */

arch/s390/include/arm64/sysreg.h

@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __S390_ARM64_SYSREG_H__
+#define __S390_ARM64_SYSREG_H__
+
+#include <linux/bits.h>
+#include <linux/stringify.h>
+#include <linux/kasan-tags.h>
+#include <linux/kconfig.h>
+
+#include <arm64/sysreg-gen.h>
+
+#endif /* __S390_ARM64_SYSREG_H__ */

arch/s390/kvm/arm64/handle_exit.c

@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/kvm_host.h>
+
+#include <arm64/esr.h>
+#include <arm64/kvm_emulate.h>
+
+typedef int (*exit_handle_fn)(struct kvm_vcpu *);
+
+#define PSCI_0_2_FN_SYSTEM_OFF		0x84000008
+#define PSCI_RET_NOT_SUPPORTED		-1
+#define PSCI_RET_INTERNAL_FAILURE	-6
+/*
+ * Temporary smc/hvc handler. Non-compliant implementation (features missing).
+ * Implements only system off so that test programs are able to end their execution.
+ * Multi-vCPU power state management and KVM_REQ_SLEEP handling are deferred
+ * to future SMP series.
+ */
+static int kvm_smccc_call_handler(struct kvm_vcpu *vcpu)
+{
+	u32 func_id = vcpu_get_reg(vcpu, 0);
+	u64 val = PSCI_RET_NOT_SUPPORTED;
+	int ret = 1;
+
+	if (func_id == PSCI_0_2_FN_SYSTEM_OFF) {
+		scoped_guard(spinlock, &vcpu->arch.mp_state_lock) {
+			WRITE_ONCE(vcpu->arch.mp_state.mp_state, KVM_MP_STATE_STOPPED);
+		}
+		memset(&vcpu->run->system_event, 0,
+		       sizeof(vcpu->run->system_event));
+		vcpu->run->system_event.type = KVM_SYSTEM_EVENT_SHUTDOWN;
+		vcpu->run->system_event.ndata = 1;
+		vcpu->run->system_event.data[0] = 0;
+		vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
+		val = PSCI_RET_INTERNAL_FAILURE;
+		ret = 0;
+	}
+	vcpu_set_reg(vcpu, 0, val);
+
+	return ret;
+}
+
+static int handle_hvc(struct kvm_vcpu *vcpu)
+{
+	vcpu->stat.hvc_exit_stat++;
+	return kvm_smccc_call_handler(vcpu);
+}
+
+static int kvm_handle_unknown_ec(struct kvm_vcpu *vcpu)
+{
+	u64 esr = kvm_vcpu_get_esr(vcpu);
+
+	kvm_pr_unimpl("Unknown exception class: esr: %#016llx -- %s\n",
+		      esr, esr_get_class_string(esr));
+
+	kvm_inject_undefined(vcpu);
+	return 1;
+}
+
+static exit_handle_fn arm_exit_handlers[] = {
+	[0 ... ESR_ELx_EC_MAX]	= kvm_handle_unknown_ec,
+	[ESR_ELx_EC_HVC64]	= handle_hvc,
+};
+
+static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu)
+{
+	u64 esr = kvm_vcpu_get_esr(vcpu);
+	u8 esr_ec = ESR_ELx_EC(esr);
+
+	return arm_exit_handlers[esr_ec];
+}
+
+/*
+ * We may be single-stepping an emulated instruction. If the emulation
+ * has been completed in the kernel, we can return to userspace with a
+ * KVM_EXIT_DEBUG, otherwise userspace needs to complete its
+ * emulation first.
+ */
+static int handle_trap_exceptions(struct kvm_vcpu *vcpu)
+{
+	exit_handle_fn exit_handler;
+
+	exit_handler = kvm_get_exit_handler(vcpu);
+	return exit_handler(vcpu);
+}
+
+/* manually copied from arch/arm64/kernel/traps.c */
+static const char * const esr_class_str[] = {
+	[0 ... ESR_ELx_EC_MAX]		= "UNRECOGNIZED EC",
+	[ESR_ELx_EC_UNKNOWN]		= "Unknown/Uncategorized",
+	[ESR_ELx_EC_WFx]		= "WFI/WFE",
+	[ESR_ELx_EC_FP_ASIMD]		= "ASIMD",
+	[ESR_ELx_EC_PAC]		= "PAC",
+	[ESR_ELx_EC_BTI]		= "BTI",
+	[ESR_ELx_EC_ILL]		= "PSTATE.IL",
+	[ESR_ELx_EC_SVC64]		= "SVC (AArch64)",
+	[ESR_ELx_EC_HVC64]		= "HVC (AArch64)",
+	[ESR_ELx_EC_SMC64]		= "SMC (AArch64)",
+	[ESR_ELx_EC_SYS64]		= "MSR/MRS (AArch64)",
+	[ESR_ELx_EC_SVE]		= "SVE",
+	[ESR_ELx_EC_ERET]		= "ERET/ERETAA/ERETAB",
+	[ESR_ELx_EC_FPAC]		= "FPAC",
+	[ESR_ELx_EC_SME]		= "SME",
+	[ESR_ELx_EC_IMP_DEF]		= "EL3 IMP DEF",
+	[ESR_ELx_EC_IABT_LOW]		= "IABT (lower EL)",
+	[ESR_ELx_EC_IABT_CUR]		= "IABT (current EL)",
+	[ESR_ELx_EC_PC_ALIGN]		= "PC Alignment",
+	[ESR_ELx_EC_DABT_LOW]		= "DABT (lower EL)",
+	[ESR_ELx_EC_DABT_CUR]		= "DABT (current EL)",
+	[ESR_ELx_EC_SP_ALIGN]		= "SP Alignment",
+	[ESR_ELx_EC_MOPS]		= "MOPS",
+	[ESR_ELx_EC_FP_EXC64]		= "FP (AArch64)",
+	[ESR_ELx_EC_GCS]		= "Guarded Control Stack",
+	[ESR_ELx_EC_SERROR]		= "SError",
+	[ESR_ELx_EC_BREAKPT_LOW]	= "Breakpoint (lower EL)",
+	[ESR_ELx_EC_BREAKPT_CUR]	= "Breakpoint (current EL)",
+	[ESR_ELx_EC_SOFTSTP_LOW]	= "Software Step (lower EL)",
+	[ESR_ELx_EC_SOFTSTP_CUR]	= "Software Step (current EL)",
+	[ESR_ELx_EC_WATCHPT_LOW]	= "Watchpoint (lower EL)",
+	[ESR_ELx_EC_WATCHPT_CUR]	= "Watchpoint (current EL)",
+	[ESR_ELx_EC_BRK64]		= "BRK (AArch64)",
+};
+
+const char *esr_get_class_string(unsigned long esr)
+{
+	return esr_class_str[ESR_ELx_EC(esr)];
+}

arch/s390/kvm/arm64/inject_fault.c

@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <arm64/kvm_emulate.h>
+
+/**
+ * kvm_inject_undefined - inject an undefined instruction into the guest
+ * @vcpu: The vCPU in which to inject the exception
+ *
+ * It is assumed that this code is called from the VCPU thread and that the
+ * VCPU therefore is not currently executing guest code.
+ */
+void kvm_inject_undefined(struct kvm_vcpu *vcpu)
+{
+	/* Stub until s390 supports arm64 sysregs TODO sysregs*/
+}
+
+int kvm_inject_sea(struct kvm_vcpu *vcpu, bool iabt, u64 addr)
+{
+	/* Stub until s390 supports arm64 sysregs TODO sysregs*/
+	return 1;
+}