summaryrefslogtreecommitdiffstats
path: root/arch/arm64/kvm/aarch32.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/arm64/kvm/aarch32.c')
-rw-r--r--arch/arm64/kvm/aarch32.c204
1 files changed, 204 insertions, 0 deletions
diff --git a/arch/arm64/kvm/aarch32.c b/arch/arm64/kvm/aarch32.c
new file mode 100644
index 000000000000..0a356aa91aa1
--- /dev/null
+++ b/arch/arm64/kvm/aarch32.c
@@ -0,0 +1,204 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * (not much of an) Emulation layer for 32bit guests.
+ *
+ * Copyright (C) 2012,2013 - ARM Ltd
+ * Author: Marc Zyngier <marc.zyngier@arm.com>
+ *
+ * based on arch/arm/kvm/emulate.c
+ * Copyright (C) 2012 - Virtual Open Systems and Columbia University
+ * Author: Christoffer Dall <c.dall@virtualopensystems.com>
+ */
+
+#include <linux/bits.h>
+#include <linux/kvm_host.h>
+#include <asm/kvm_emulate.h>
+#include <asm/kvm_hyp.h>
+
+#define DFSR_FSC_EXTABT_LPAE 0x10
+#define DFSR_FSC_EXTABT_nLPAE 0x08
+#define DFSR_LPAE BIT(9)
+
+/*
+ * Table taken from ARMv8 ARM DDI0487B-B, table G1-10.
+ */
+static const u8 return_offsets[8][2] = {
+ [0] = { 0, 0 }, /* Reset, unused */
+ [1] = { 4, 2 }, /* Undefined */
+ [2] = { 0, 0 }, /* SVC, unused */
+ [3] = { 4, 4 }, /* Prefetch abort */
+ [4] = { 8, 8 }, /* Data abort */
+ [5] = { 0, 0 }, /* HVC, unused */
+ [6] = { 4, 4 }, /* IRQ, unused */
+ [7] = { 4, 4 }, /* FIQ, unused */
+};
+
+/*
+ * When an exception is taken, most CPSR fields are left unchanged in the
+ * handler. However, some are explicitly overridden (e.g. M[4:0]).
+ *
+ * The SPSR/SPSR_ELx layouts differ, and the below is intended to work with
+ * either format. Note: SPSR.J bit doesn't exist in SPSR_ELx, but this bit was
+ * obsoleted by the ARMv7 virtualization extensions and is RES0.
+ *
+ * For the SPSR layout seen from AArch32, see:
+ * - ARM DDI 0406C.d, page B1-1148
+ * - ARM DDI 0487E.a, page G8-6264
+ *
+ * For the SPSR_ELx layout for AArch32 seen from AArch64, see:
+ * - ARM DDI 0487E.a, page C5-426
+ *
+ * Here we manipulate the fields in order of the AArch32 SPSR_ELx layout, from
+ * MSB to LSB.
+ */
+static unsigned long get_except32_cpsr(struct kvm_vcpu *vcpu, u32 mode)
+{
+ u32 sctlr = vcpu_cp15(vcpu, c1_SCTLR);
+ unsigned long old, new;
+
+ old = *vcpu_cpsr(vcpu);
+ new = 0;
+
+ new |= (old & PSR_AA32_N_BIT);
+ new |= (old & PSR_AA32_Z_BIT);
+ new |= (old & PSR_AA32_C_BIT);
+ new |= (old & PSR_AA32_V_BIT);
+ new |= (old & PSR_AA32_Q_BIT);
+
+ // CPSR.IT[7:0] are set to zero upon any exception
+ // See ARM DDI 0487E.a, section G1.12.3
+ // See ARM DDI 0406C.d, section B1.8.3
+
+ new |= (old & PSR_AA32_DIT_BIT);
+
+ // CPSR.SSBS is set to SCTLR.DSSBS upon any exception
+ // See ARM DDI 0487E.a, page G8-6244
+ if (sctlr & BIT(31))
+ new |= PSR_AA32_SSBS_BIT;
+
+ // CPSR.PAN is unchanged unless SCTLR.SPAN == 0b0
+ // SCTLR.SPAN is RES1 when ARMv8.1-PAN is not implemented
+ // See ARM DDI 0487E.a, page G8-6246
+ new |= (old & PSR_AA32_PAN_BIT);
+ if (!(sctlr & BIT(23)))
+ new |= PSR_AA32_PAN_BIT;
+
+ // SS does not exist in AArch32, so ignore
+
+ // CPSR.IL is set to zero upon any exception
+ // See ARM DDI 0487E.a, page G1-5527
+
+ new |= (old & PSR_AA32_GE_MASK);
+
+ // CPSR.IT[7:0] are set to zero upon any exception
+ // See prior comment above
+
+ // CPSR.E is set to SCTLR.EE upon any exception
+ // See ARM DDI 0487E.a, page G8-6245
+ // See ARM DDI 0406C.d, page B4-1701
+ if (sctlr & BIT(25))
+ new |= PSR_AA32_E_BIT;
+
+ // CPSR.A is unchanged upon an exception to Undefined, Supervisor
+ // CPSR.A is set upon an exception to other modes
+ // See ARM DDI 0487E.a, pages G1-5515 to G1-5516
+ // See ARM DDI 0406C.d, page B1-1182
+ new |= (old & PSR_AA32_A_BIT);
+ if (mode != PSR_AA32_MODE_UND && mode != PSR_AA32_MODE_SVC)
+ new |= PSR_AA32_A_BIT;
+
+ // CPSR.I is set upon any exception
+ // See ARM DDI 0487E.a, pages G1-5515 to G1-5516
+ // See ARM DDI 0406C.d, page B1-1182
+ new |= PSR_AA32_I_BIT;
+
+ // CPSR.F is set upon an exception to FIQ
+ // CPSR.F is unchanged upon an exception to other modes
+ // See ARM DDI 0487E.a, pages G1-5515 to G1-5516
+ // See ARM DDI 0406C.d, page B1-1182
+ new |= (old & PSR_AA32_F_BIT);
+ if (mode == PSR_AA32_MODE_FIQ)
+ new |= PSR_AA32_F_BIT;
+
+ // CPSR.T is set to SCTLR.TE upon any exception
+ // See ARM DDI 0487E.a, page G8-5514
+ // See ARM DDI 0406C.d, page B1-1181
+ if (sctlr & BIT(30))
+ new |= PSR_AA32_T_BIT;
+
+ new |= mode;
+
+ return new;
+}
+
+static void prepare_fault32(struct kvm_vcpu *vcpu, u32 mode, u32 vect_offset)
+{
+ unsigned long spsr = *vcpu_cpsr(vcpu);
+ bool is_thumb = (spsr & PSR_AA32_T_BIT);
+ u32 return_offset = return_offsets[vect_offset >> 2][is_thumb];
+ u32 sctlr = vcpu_cp15(vcpu, c1_SCTLR);
+
+ *vcpu_cpsr(vcpu) = get_except32_cpsr(vcpu, mode);
+
+ /* Note: These now point to the banked copies */
+ vcpu_write_spsr(vcpu, host_spsr_to_spsr32(spsr));
+ *vcpu_reg32(vcpu, 14) = *vcpu_pc(vcpu) + return_offset;
+
+ /* Branch to exception vector */
+ if (sctlr & (1 << 13))
+ vect_offset += 0xffff0000;
+ else /* always have security exceptions */
+ vect_offset += vcpu_cp15(vcpu, c12_VBAR);
+
+ *vcpu_pc(vcpu) = vect_offset;
+}
+
+void kvm_inject_undef32(struct kvm_vcpu *vcpu)
+{
+ prepare_fault32(vcpu, PSR_AA32_MODE_UND, 4);
+}
+
+/*
+ * Modelled after TakeDataAbortException() and TakePrefetchAbortException
+ * pseudocode.
+ */
+static void inject_abt32(struct kvm_vcpu *vcpu, bool is_pabt,
+ unsigned long addr)
+{
+ u32 vect_offset;
+ u32 *far, *fsr;
+ bool is_lpae;
+
+ if (is_pabt) {
+ vect_offset = 12;
+ far = &vcpu_cp15(vcpu, c6_IFAR);
+ fsr = &vcpu_cp15(vcpu, c5_IFSR);
+ } else { /* !iabt */
+ vect_offset = 16;
+ far = &vcpu_cp15(vcpu, c6_DFAR);
+ fsr = &vcpu_cp15(vcpu, c5_DFSR);
+ }
+
+ prepare_fault32(vcpu, PSR_AA32_MODE_ABT, vect_offset);
+
+ *far = addr;
+
+ /* Give the guest an IMPLEMENTATION DEFINED exception */
+ is_lpae = (vcpu_cp15(vcpu, c2_TTBCR) >> 31);
+ if (is_lpae) {
+ *fsr = DFSR_LPAE | DFSR_FSC_EXTABT_LPAE;
+ } else {
+ /* no need to shuffle FS[4] into DFSR[10] as its 0 */
+ *fsr = DFSR_FSC_EXTABT_nLPAE;
+ }
+}
+
+void kvm_inject_dabt32(struct kvm_vcpu *vcpu, unsigned long addr)
+{
+ inject_abt32(vcpu, false, addr);
+}
+
+void kvm_inject_pabt32(struct kvm_vcpu *vcpu, unsigned long addr)
+{
+ inject_abt32(vcpu, true, addr);
+}