KVM: arm64: Get rid of the AArch32 register mapping code

The only use of the register mapping code was for the sake of the LR
mapping, which we trivially solved in a previous patch. Get rid of
the whole thing now.
Signed-off-by: Marc Zyngier <maz@kernel.org>

arch/arm64/include/asm/kvm_emulate.h

@@ -33,8 +33,6 @@ enum exception_type {
 	except_type_serror	= 0x180,
 };
 
-unsigned long *vcpu_reg32(const struct kvm_vcpu *vcpu, u8 reg_num);
-
 bool kvm_condition_valid32(const struct kvm_vcpu *vcpu);
 void kvm_skip_instr32(struct kvm_vcpu *vcpu);
 

arch/arm64/kvm/Makefile

@@ -13,7 +13,7 @@ obj-$(CONFIG_KVM) += hyp/
 kvm-y := $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/eventfd.o \
 	 $(KVM)/vfio.o $(KVM)/irqchip.o \
 	 arm.o mmu.o mmio.o psci.o perf.o hypercalls.o pvtime.o \
-	 inject_fault.o regmap.o va_layout.o handle_exit.o \
+	 inject_fault.o va_layout.o handle_exit.o \
 	 guest.o debug.o reset.o sys_regs.o \
 	 vgic-sys-reg-v3.o fpsimd.o pmu.o \
 	 arch_timer.o \

arch/arm64/kvm/guest.c

@@ -252,10 +252,32 @@ static int set_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 	memcpy(addr, valp, KVM_REG_SIZE(reg->id));
 
 	if (*vcpu_cpsr(vcpu) & PSR_MODE32_BIT) {
-		int i;
+		int i, nr_reg;
 
-		for (i = 0; i < 16; i++)
-			*vcpu_reg32(vcpu, i) = (u32)*vcpu_reg32(vcpu, i);
+		switch (*vcpu_cpsr(vcpu)) {
+		/*
+		 * Either we are dealing with user mode, and only the
+		 * first 15 registers (+ PC) must be narrowed to 32bit.
+		 * AArch32 r0-r14 conveniently map to AArch64 x0-x14.
+		 */
+		case PSR_AA32_MODE_USR:
+		case PSR_AA32_MODE_SYS:
+			nr_reg = 15;
+			break;
+
+		/*
+		 * Otherwide, this is a priviledged mode, and *all* the
+		 * registers must be narrowed to 32bit.
+		 */
+		default:
+			nr_reg = 31;
+			break;
+		}
+
+		for (i = 0; i < nr_reg; i++)
+			vcpu_set_reg(vcpu, i, (u32)vcpu_get_reg(vcpu, i));
+
+		*vcpu_pc(vcpu) = (u32)*vcpu_pc(vcpu);
 	}
 out:
 	return err;

arch/arm64/kvm/regmap.c

-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * Copyright (C) 2012,2013 - ARM Ltd
- * Author: Marc Zyngier <marc.zyngier@arm.com>
- *
- * Derived from arch/arm/kvm/emulate.c:
- * Copyright (C) 2012 - Virtual Open Systems and Columbia University
- * Author: Christoffer Dall <c.dall@virtualopensystems.com>
- */
-
-#include <linux/mm.h>
-#include <linux/kvm_host.h>
-#include <asm/kvm_emulate.h>
-#include <asm/ptrace.h>
-
-#define VCPU_NR_MODES 6
-#define REG_OFFSET(_reg) \
-	(offsetof(struct user_pt_regs, _reg) / sizeof(unsigned long))
-
-#define USR_REG_OFFSET(R) REG_OFFSET(compat_usr(R))
-
-static const unsigned long vcpu_reg_offsets[VCPU_NR_MODES][16] = {
-	/* USR Registers */
-	{
-		USR_REG_OFFSET(0), USR_REG_OFFSET(1), USR_REG_OFFSET(2),
-		USR_REG_OFFSET(3), USR_REG_OFFSET(4), USR_REG_OFFSET(5),
-		USR_REG_OFFSET(6), USR_REG_OFFSET(7), USR_REG_OFFSET(8),
-		USR_REG_OFFSET(9), USR_REG_OFFSET(10), USR_REG_OFFSET(11),
-		USR_REG_OFFSET(12), USR_REG_OFFSET(13),	USR_REG_OFFSET(14),
-		REG_OFFSET(pc)
-	},
-
-	/* FIQ Registers */
-	{
-		USR_REG_OFFSET(0), USR_REG_OFFSET(1), USR_REG_OFFSET(2),
-		USR_REG_OFFSET(3), USR_REG_OFFSET(4), USR_REG_OFFSET(5),
-		USR_REG_OFFSET(6), USR_REG_OFFSET(7),
-		REG_OFFSET(compat_r8_fiq),  /* r8 */
-		REG_OFFSET(compat_r9_fiq),  /* r9 */
-		REG_OFFSET(compat_r10_fiq), /* r10 */
-		REG_OFFSET(compat_r11_fiq), /* r11 */
-		REG_OFFSET(compat_r12_fiq), /* r12 */
-		REG_OFFSET(compat_sp_fiq),  /* r13 */
-		REG_OFFSET(compat_lr_fiq),  /* r14 */
-		REG_OFFSET(pc)
-	},
-
-	/* IRQ Registers */
-	{
-		USR_REG_OFFSET(0), USR_REG_OFFSET(1), USR_REG_OFFSET(2),
-		USR_REG_OFFSET(3), USR_REG_OFFSET(4), USR_REG_OFFSET(5),
-		USR_REG_OFFSET(6), USR_REG_OFFSET(7), USR_REG_OFFSET(8),
-		USR_REG_OFFSET(9), USR_REG_OFFSET(10), USR_REG_OFFSET(11),
-		USR_REG_OFFSET(12),
-		REG_OFFSET(compat_sp_irq), /* r13 */
-		REG_OFFSET(compat_lr_irq), /* r14 */
-		REG_OFFSET(pc)
-	},
-
-	/* SVC Registers */
-	{
-		USR_REG_OFFSET(0), USR_REG_OFFSET(1), USR_REG_OFFSET(2),
-		USR_REG_OFFSET(3), USR_REG_OFFSET(4), USR_REG_OFFSET(5),
-		USR_REG_OFFSET(6), USR_REG_OFFSET(7), USR_REG_OFFSET(8),
-		USR_REG_OFFSET(9), USR_REG_OFFSET(10), USR_REG_OFFSET(11),
-		USR_REG_OFFSET(12),
-		REG_OFFSET(compat_sp_svc), /* r13 */
-		REG_OFFSET(compat_lr_svc), /* r14 */
-		REG_OFFSET(pc)
-	},
-
-	/* ABT Registers */
-	{
-		USR_REG_OFFSET(0), USR_REG_OFFSET(1), USR_REG_OFFSET(2),
-		USR_REG_OFFSET(3), USR_REG_OFFSET(4), USR_REG_OFFSET(5),
-		USR_REG_OFFSET(6), USR_REG_OFFSET(7), USR_REG_OFFSET(8),
-		USR_REG_OFFSET(9), USR_REG_OFFSET(10), USR_REG_OFFSET(11),
-		USR_REG_OFFSET(12),
-		REG_OFFSET(compat_sp_abt), /* r13 */
-		REG_OFFSET(compat_lr_abt), /* r14 */
-		REG_OFFSET(pc)
-	},
-
-	/* UND Registers */
-	{
-		USR_REG_OFFSET(0), USR_REG_OFFSET(1), USR_REG_OFFSET(2),
-		USR_REG_OFFSET(3), USR_REG_OFFSET(4), USR_REG_OFFSET(5),
-		USR_REG_OFFSET(6), USR_REG_OFFSET(7), USR_REG_OFFSET(8),
-		USR_REG_OFFSET(9), USR_REG_OFFSET(10), USR_REG_OFFSET(11),
-		USR_REG_OFFSET(12),
-		REG_OFFSET(compat_sp_und), /* r13 */
-		REG_OFFSET(compat_lr_und), /* r14 */
-		REG_OFFSET(pc)
-	},
-};
-
-/*
- * Return a pointer to the register number valid in the current mode of
- * the virtual CPU.
- */
-unsigned long *vcpu_reg32(const struct kvm_vcpu *vcpu, u8 reg_num)
-{
-	unsigned long *reg_array = (unsigned long *)&vcpu->arch.ctxt.regs;
-	unsigned long mode = *vcpu_cpsr(vcpu) & PSR_AA32_MODE_MASK;
-
-	switch (mode) {
-	case PSR_AA32_MODE_USR ... PSR_AA32_MODE_SVC:
-		mode &= ~PSR_MODE32_BIT; /* 0 ... 3 */
-		break;
-
-	case PSR_AA32_MODE_ABT:
-		mode = 4;
-		break;
-
-	case PSR_AA32_MODE_UND:
-		mode = 5;
-		break;
-
-	case PSR_AA32_MODE_SYS:
-		mode = 0;	/* SYS maps to USR */
-		break;
-
-	default:
-		BUG();
-	}
-
-	return reg_array + vcpu_reg_offsets[mode][reg_num];
-}