[PATCH v8 20/29] s390: Introduce Start Arm Execution instruction

[Steffen Eiden <seiden@linux.ibm.com>]

The Start Arm Execution (SAE) instruction is the centerpiece for
executing arm64 (KVM) guests on s390. Its purpose is, similar to SIE, to
enable accelerated execution of arm64 virtual machines. SAE expects the
physical address of a control block as the only argument.

The host is responsible to save & restore
 - GPRs 0-13
 - access register 0-15
 - breaking event register (BEAR)
 - vector/floating point registers
between SAE executions to guarantee host consistency.

GPRs and BEAR are save and restores in the asm functions. The other
register are handled in within C code. Access registers are handled in a
later patch and SVEs will be handled when they are introduced in a
future series. Most arm64 registers are handled by a satellite block
called save_area. Some registers, frequently used by hypervisors, are
placed into the SAE control block itself.

Enlighten asm/kvm_host_types.h for the new header variant. The new
header is chosen instead of asm/kvm_host_s390_types.h if KVM_S390_ARM64
is defined.

Co-developed-by: Andreas Grapentin <gra@linux.ibm.com>
Signed-off-by: Andreas Grapentin <gra@linux.ibm.com>
Co-developed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
---
 arch/s390/include/asm/asm-prototypes.h       |   1 +
 arch/s390/include/asm/kvm_host_arm64_types.h | 124 +++++++++++++++++++
 arch/s390/include/asm/kvm_host_types.h       |   4 +
 arch/s390/include/asm/sae.h                  |  58 +++++++++
 arch/s390/include/asm/stacktrace.h           |   5 +
 arch/s390/kernel/asm-offsets.c               |   1 +
 arch/s390/kernel/entry.S                     |  22 ++++
 arch/s390/tools/opcodes.txt                  |   3 +
 8 files changed, 218 insertions(+)
 create mode 100644 arch/s390/include/asm/kvm_host_arm64_types.h
 create mode 100644 arch/s390/include/asm/sae.h

diff --git a/arch/s390/include/asm/asm-prototypes.h b/arch/s390/include/asm/asm-prototypes.h
index d4da4436d02b..faa2afb259a1 100644
--- a/arch/s390/include/asm/asm-prototypes.h
+++ b/arch/s390/include/asm/asm-prototypes.h
@@ -6,6 +6,7 @@
 #include <asm/bug.h>
 #include <asm/fpu.h>
 #include <asm/nospec-branch.h>
+#include <asm/sae.h>
 #include <asm-generic/asm-prototypes.h>
 
 #endif /* _ASM_S390_PROTOTYPES_H */
diff --git a/arch/s390/include/asm/kvm_host_arm64_types.h b/arch/s390/include/asm/kvm_host_arm64_types.h
new file mode 100644
index 000000000000..8783a66d3029
--- /dev/null
+++ b/arch/s390/include/asm/kvm_host_arm64_types.h
@@ -0,0 +1,124 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef ASM_KVM_HOST_ARM64_TYPES_H
+#define ASM_KVM_HOST_ARM64_TYPES_H
+
+#include <linux/types.h>
+#include <linux/kvm_types.h>
+#include <linux/compiler_attributes.h>
+#include <asm/page.h>
+#include <asm/fault.h>
+
+struct kvm_sae_block {
+	u64	_0000[16];		/* 0x0000 */
+#define SAE_ICPTR_SPURIOUS			0x00
+#define SAE_ICPTR_VALIDITY			0x01
+#define SAE_ICPTR_HOST_ACCESS_EXCEPTION		0x02
+#define SAE_ICPTR_SYNCHRONOUS_EXCEPTION		0x03
+#define SAE_ICPTR_TIMER				0x04
+#define SAE_ICPTR_PE_INTERCOMM			0x05
+#define SAE_ICPTR_GUEST_ADDRESS_SIZE		0x06
+#define SAE_ICPTR_STOP				0x07
+#define SAE_ICPTR_MIO_ADDRESS			0x08
+#define SAE_ICPTR_PMU				0x09
+#define SAE_ICPTR_MAINTENANCE			0x0a
+	u8	icptr;			/* 0x0080 */
+	u8	_0081[7];		/* 0x0081 */
+	u64	scad;			/* 0x0088 */
+	u64	_0090[16];		/* 0x0090 */
+	u32	cntp_ctl;		/* 0x0110 */
+	u32	cntv_ctl;		/* 0x0114 */
+	u8	irq_ctl;		/* 0x0118 */
+	u8	_0119[7];		/* 0x0119 */
+	struct {
+		u64	ich_hcr_el2;	/* 0x0120 */
+		u64	ich_vmcr_el2;	/* 0x0128 */
+		u64	ich_ap0r0_el2;	/* 0x0130 */
+		u64	ich_ap1r0_el2;	/* 0x0138 */
+		u64	_0140[2];	/* 0x0140 */
+		u64	ich_lrn_el2[4];	/* 0x0150 */
+		u64	_0170[4];	/* 0x0170 */
+	} ic_regs;
+	u64	_0190[12];		/* 0x0190 */
+	u64	contextidr_el1;		/* 0x01f0 */
+	u32	wip;			/* 0x01f8 */
+	u32	_01fc;			/* 0x01fc */
+#define SAE_SD_FORMAT_0                 0x00
+	u8	sdf;			/* 0x0200  */
+	u8	_0201[7];		/* 0x0201  */
+	u64	mso;			/* 0x0208  */
+	u64	msl;			/* 0x0210  */
+	u64	hbasce;			/* 0x0218  */
+	u64	_0220;			/* 0x0220  */
+	u64	gpto;			/* 0x0228  */
+	u64	ic;			/* 0x0230  */
+	u64	ec;			/* 0x0238  */
+	u64	save_area;		/* 0x0240  */
+	u64	_0248[7];		/* 0x0248  */
+	u8	_0280[6];		/* 0x0280  */
+	u16	lrcpua;			/* 0x0286  */
+	u64	pstate;			/* 0x0288  */
+	u64	pc;			/* 0x0290  */
+	u64	sp_el0;			/* 0x0298  */
+	u64	sp_el1;			/* 0x02a0  */
+	u64	_02a8;			/* 0x02a8  */
+	struct {			/* 0x02b0  */
+		u32	_fpcr_res0;
+		u32	fpcr;
+	};
+	struct {			/* 0x02b8  */
+		u32	_fpsr_res0;
+		u32	fpsr;
+	};
+	u16	sve_pregs[16];		/* 0x02c0  */
+	u16	sve_ffr;		/* 0x02e0  */
+	u8	_02e2[6];		/* 0x02e2  */
+	u64	_02e8[3];		/* 0x02e8  */
+
+	u64	gpr[31];		/* 0x0300  */
+	u64	_03f8;			/* 0x03f8  */
+
+	union {
+		u64	icptd[8];		/* 0x0400 */
+		/* validity-interception reason; icptr 0x01 */
+		u16 vir;			/* 0x0400 */
+		/* host access interception details; icptr 0x02 */
+		struct {
+			u64		esr_el2;	/* 0x0400 */
+			u8		_0408[6];	/* 0x0408 */
+			u16		pic;		/* 0x040e */
+			union teid	teid;		/* 0x0410 */
+			gva_t		far_el2;	/* 0x0418 */
+			gva_t		vaddr;		/* 0x0420 */
+			u64		suppl;		/* 0x0428 */
+			u8		gltl;		/* 0x0430 */
+			u8		_0431[7];	/* 0x0431 */
+			u64		_0438;		/* 0x0438 */
+		} hai;
+		/* exception-interception details; icptr 0x03 */
+		struct {
+			u64	esr_el2;		/* 0x0400 */
+			u64	_0408[2];		/* 0x0408 */
+			gva_t	far_el2;		/* 0x0418 */
+		} trap;
+		/* timer-interception reason; icptr 0x04 */
+#define SAE_IR_TIMER_ID_VIRT		BIT(6)
+#define SAE_IR_TIMER_ID_PHYS		BIT(7)
+		u8	tir;			/* 0x0400 */
+	};
+	u64	_0440[376];			/* 0x0440 */
+} __packed __aligned(PAGE_SIZE);
+static_assert(sizeof(struct kvm_sae_block) == PAGE_SIZE);
+
+struct kvm_sae_save_area {
+#define SAE_SAVE_AREA_FORMAT_0	0x00
+	u8	saf;		/* 0x0000 */
+	u8	_0001[5];	/* 0x0001 */
+#define SAE_SAS_VALID		BIT(0)
+	u16	sas;		/* 0x0006 */
+	u64	sdo;		/* 0x0008 */
+	u64	_0010[2];	/* 0x0010 */
+	u64	regs[508];	/* 0x0020 */
+} __packed __aligned(PAGE_SIZE);
+static_assert(sizeof(struct kvm_sae_save_area) == PAGE_SIZE);
+
+#endif /* ASM_KVM_HOST_ARM64_TYPES_H */
diff --git a/arch/s390/include/asm/kvm_host_types.h b/arch/s390/include/asm/kvm_host_types.h
index e5bdba07cab0..d308739ebcf5 100644
--- a/arch/s390/include/asm/kvm_host_types.h
+++ b/arch/s390/include/asm/kvm_host_types.h
@@ -3,6 +3,10 @@
 #ifndef ASM_KVM_HOST_TYPES_H
 #define ASM_KVM_HOST_TYPES_H
 
+#ifdef KVM_S390_ARM64
+#include <asm/kvm_host_arm64_types.h>
+#else
 #include <asm/kvm_host_s390_types.h>
+#endif /* KVM_S390_ARM64 */
 
 #endif /* ASM_KVM_HOST_TYPES_H */
diff --git a/arch/s390/include/asm/sae.h b/arch/s390/include/asm/sae.h
new file mode 100644
index 000000000000..b644e65c4e37
--- /dev/null
+++ b/arch/s390/include/asm/sae.h
@@ -0,0 +1,58 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_S390_SAE_H
+#define __ASM_S390_SAE_H
+
+#include <linux/linkage.h>
+#include <linux/types.h>
+
+#ifndef __ASSEMBLER__
+
+/* defined in arch/s390/kernel/entry.S */
+asmlinkage void __sae64a(phys_addr_t sae_block_phys);
+
+#include <linux/io.h>
+#include <asm/kvm_host_arm64_types.h>
+
+/**
+ * sae64a() - Start Arm Execution
+ * @sae_block: pointer to the SAE control block
+ */
+static inline void sae64a(struct kvm_sae_block *sae_block)
+{
+	__sae64a(virt_to_phys(sae_block));
+}
+
+/**
+ * stiasrm() - STore and Invalidate Arm System Register Multiple
+ * @save_area: Pointer to SAE save area
+ *
+ * Store the guest system registers to the save area.
+ * The values in the guest are no longer valid.
+ */
+static __always_inline void stiasrm(struct kvm_sae_save_area *save_area)
+{
+	asm volatile(
+		"	.insn	rre,0xb9a70000,%[r1],0\n"
+		: "+m"(*save_area)
+		: [r1] "a"(save_area)
+	);
+}
+
+/**
+ * lasrm() - Load Arm System Register Multiple
+ *
+ * @save_area: Pointer to SAE save area
+ *
+ * Load the system registers from save_area into the guest.
+ */
+static __always_inline void lasrm(struct kvm_sae_save_area *save_area)
+{
+	asm volatile(
+		"	.insn	rre,0xb9a60000,%[r1],0\n"
+		:
+		: "m"(*save_area), [r1] "a"(save_area)
+	);
+}
+
+#endif /* !__ASSEMBLER__ */
+#endif /* __ASM_S390_SAE_H */
diff --git a/arch/s390/include/asm/stacktrace.h b/arch/s390/include/asm/stacktrace.h
index ac3606c3babe..2d332d7c8145 100644
--- a/arch/s390/include/asm/stacktrace.h
+++ b/arch/s390/include/asm/stacktrace.h
@@ -59,6 +59,7 @@ static inline bool on_stack(struct stack_info *info,
 struct stack_frame {
 	union {
 		unsigned long empty[9];
+		/* SIE stack frame */
 		struct {
 			unsigned long sie_control_block;
 			unsigned long sie_savearea;
@@ -68,6 +69,10 @@ struct stack_frame {
 			unsigned long sie_guest_asce;
 			unsigned long sie_irq;
 		};
+		/* SAE stack frame */
+		struct {
+			unsigned long sae_bear;
+		};
 	};
 	unsigned long gprs[10];
 	unsigned long back_chain;
diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c
index f6dd2b67dcee..f9f9c2246074 100644
--- a/arch/s390/kernel/asm-offsets.c
+++ b/arch/s390/kernel/asm-offsets.c
@@ -70,6 +70,7 @@ int main(void)
 	OFFSET(__SF_SIE_CONTROL_PHYS, stack_frame, sie_control_block_phys);
 	OFFSET(__SF_SIE_GUEST_ASCE, stack_frame, sie_guest_asce);
 	OFFSET(__SF_SIE_IRQ, stack_frame, sie_irq);
+	OFFSET(__SF_SAE_BEAR, stack_frame, sae_bear);
 	DEFINE(STACK_FRAME_OVERHEAD, sizeof(struct stack_frame));
 	BLANK();
 	OFFSET(__SFUSER_BACKCHAIN, stack_frame_user, back_chain);
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 10dd9bbdf985..af515f2b6c11 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -245,6 +245,28 @@ EXPORT_SYMBOL(__sie64a)
 EXPORT_SYMBOL(sie_exit)
 #endif
 
+#if IS_ENABLED(CONFIG_KVM)
+/*
+ * __sae64a calling convention:
+ * %r2 pointer to sae control block physical address
+ */
+SYM_FUNC_START(__sae64a)
+	stmg	%r6,%r14,__SF_GPRS(%r15)	# store kernel registers
+	STBEAR	__SF_SAE_BEAR(%r15)		# save breaking event address register
+	.insn	rre,0xb9a50000,%r2,0		# Start Arm Execution
+	LBEAR	__SF_SAE_BEAR(%r15)		# restore breaking event address register
+	lmg	%r6,%r14,__SF_GPRS(%r15)	# restore kernel registers
+	xgr	%r0,%r0				# clear guest registers to
+	xgr	%r1,%r1				# prevent speculative use
+	xgr	%r2,%r2
+	xgr	%r3,%r3
+	xgr	%r4,%r4
+	xgr	%r5,%r5
+	BR_EX	%r14
+SYM_FUNC_END(__sae64a)
+EXPORT_SYMBOL(__sae64a)
+#endif
+
 /*
  * SVC interrupt handler routine. System calls are synchronous events and
  * are entered with interrupts disabled.
diff --git a/arch/s390/tools/opcodes.txt b/arch/s390/tools/opcodes.txt
index def2659f6602..0e4773c94af0 100644
--- a/arch/s390/tools/opcodes.txt
+++ b/arch/s390/tools/opcodes.txt
@@ -594,6 +594,9 @@ b9a0	clp	RRF_U0RR
 b9a1	tpei	RRE_RR
 b9a2	ptf	RRE_R0
 b9a4	uvc	RRF_URR
+b9a5	sae	RRE_R0
+b9a6	lasrm	RRE_R0
+b9a7	stiasrm	RRE_R0
 b9aa	lptea	RRF_RURR2
 b9ab	essa	RRF_U0RR
 b9ac	irbm	RRE_RR
-- 
2.53.0