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linux/arch/arm64/kvm/hyp/exception.c
Marc Zyngier 41613b519c KVM: arm64: Inject AArch32 exceptions from HYP 
Similarly to what has been done for AArch64, move the AArch32 exception
injection to HYP.

In order to not use the regmap selection code at EL2, simplify the code
populating the target mode's LR register by useing the compatibility
aliases for LR_abt and LR_und.

We also introduce new accessors for SPSR_abt and SPSR_und, and
move VBAR/SCTLR to using the AArch64 accessors (the use of the AArch32
names was an ARMv7 leftover).

Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
2020-11-10 08:34:26 +00:00

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Fault injection for both 32 and 64bit 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 <hyp/adjust_pc.h>
#include <linux/kvm_host.h>
#include <asm/kvm_emulate.h>
#if !defined (__KVM_NVHE_HYPERVISOR__) && !defined (__KVM_VHE_HYPERVISOR__)
#error Hypervisor code only!
#endif
static inline u64 __vcpu_read_sys_reg(const struct kvm_vcpu *vcpu, int reg)
{
u64 val;
if (__vcpu_read_sys_reg_from_cpu(reg, &val))
return val;
return __vcpu_sys_reg(vcpu, reg);
}
static inline void __vcpu_write_sys_reg(struct kvm_vcpu *vcpu, u64 val, int reg)
{
if (__vcpu_write_sys_reg_to_cpu(val, reg))
return;
__vcpu_sys_reg(vcpu, reg) = val;
}
static void __vcpu_write_spsr(struct kvm_vcpu *vcpu, u64 val)
{
write_sysreg_el1(val, SYS_SPSR);
}
static void __vcpu_write_spsr_abt(struct kvm_vcpu *vcpu, u64 val)
{
if (has_vhe())
write_sysreg(val, spsr_abt);
else
vcpu->arch.ctxt.spsr_abt = val;
}
static void __vcpu_write_spsr_und(struct kvm_vcpu *vcpu, u64 val)
{
if (has_vhe())
write_sysreg(val, spsr_und);
else
vcpu->arch.ctxt.spsr_und = val;
}
/*
* This performs the exception entry at a given EL (@target_mode), stashing PC
* and PSTATE into ELR and SPSR respectively, and compute the new PC/PSTATE.
* The EL passed to this function *must* be a non-secure, privileged mode with
* bit 0 being set (PSTATE.SP == 1).
*
* When an exception is taken, most PSTATE fields are left unchanged in the
* handler. However, some are explicitly overridden (e.g. M[4:0]). Luckily all
* of the inherited bits have the same position in the AArch64/AArch32 SPSR_ELx
* layouts, so we don't need to shuffle these for exceptions from AArch32 EL0.
*
* For the SPSR_ELx layout for AArch64, see ARM DDI 0487E.a page C5-429.
* For the SPSR_ELx layout for AArch32, see ARM DDI 0487E.a page C5-426.
*
* Here we manipulate the fields in order of the AArch64 SPSR_ELx layout, from
* MSB to LSB.
*/
static void enter_exception64(struct kvm_vcpu *vcpu, unsigned long target_mode,
enum exception_type type)
{
unsigned long sctlr, vbar, old, new, mode;
u64 exc_offset;
mode = *vcpu_cpsr(vcpu) & (PSR_MODE_MASK | PSR_MODE32_BIT);
if (mode == target_mode)
exc_offset = CURRENT_EL_SP_ELx_VECTOR;
else if ((mode | PSR_MODE_THREAD_BIT) == target_mode)
exc_offset = CURRENT_EL_SP_EL0_VECTOR;
else if (!(mode & PSR_MODE32_BIT))
exc_offset = LOWER_EL_AArch64_VECTOR;
else
exc_offset = LOWER_EL_AArch32_VECTOR;
switch (target_mode) {
case PSR_MODE_EL1h:
vbar = __vcpu_read_sys_reg(vcpu, VBAR_EL1);
sctlr = __vcpu_read_sys_reg(vcpu, SCTLR_EL1);
__vcpu_write_sys_reg(vcpu, *vcpu_pc(vcpu), ELR_EL1);
break;
default:
/* Don't do that */
BUG();
}
*vcpu_pc(vcpu) = vbar + exc_offset + type;
old = *vcpu_cpsr(vcpu);
new = 0;
new |= (old & PSR_N_BIT);
new |= (old & PSR_Z_BIT);
new |= (old & PSR_C_BIT);
new |= (old & PSR_V_BIT);
// TODO: TCO (if/when ARMv8.5-MemTag is exposed to guests)
new |= (old & PSR_DIT_BIT);
// PSTATE.UAO is set to zero upon any exception to AArch64
// See ARM DDI 0487E.a, page D5-2579.
// PSTATE.PAN is unchanged unless SCTLR_ELx.SPAN == 0b0
// SCTLR_ELx.SPAN is RES1 when ARMv8.1-PAN is not implemented
// See ARM DDI 0487E.a, page D5-2578.
new |= (old & PSR_PAN_BIT);
if (!(sctlr & SCTLR_EL1_SPAN))
new |= PSR_PAN_BIT;
// PSTATE.SS is set to zero upon any exception to AArch64
// See ARM DDI 0487E.a, page D2-2452.
// PSTATE.IL is set to zero upon any exception to AArch64
// See ARM DDI 0487E.a, page D1-2306.
// PSTATE.SSBS is set to SCTLR_ELx.DSSBS upon any exception to AArch64
// See ARM DDI 0487E.a, page D13-3258
if (sctlr & SCTLR_ELx_DSSBS)
new |= PSR_SSBS_BIT;
// PSTATE.BTYPE is set to zero upon any exception to AArch64
// See ARM DDI 0487E.a, pages D1-2293 to D1-2294.
new |= PSR_D_BIT;
new |= PSR_A_BIT;
new |= PSR_I_BIT;
new |= PSR_F_BIT;
new |= target_mode;
*vcpu_cpsr(vcpu) = new;
__vcpu_write_spsr(vcpu, old);
}
/*
* 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_read_sys_reg(vcpu, SCTLR_EL1);
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;
}
/*
* 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 */
};
static void enter_exception32(struct kvm_vcpu *vcpu, u32 mode, u32 vect_offset)
{
unsigned long spsr = *vcpu_cpsr(vcpu);
bool is_thumb = (spsr & PSR_AA32_T_BIT);
u32 sctlr = __vcpu_read_sys_reg(vcpu, SCTLR_EL1);
u32 return_address;
*vcpu_cpsr(vcpu) = get_except32_cpsr(vcpu, mode);
return_address = *vcpu_pc(vcpu);
return_address += return_offsets[vect_offset >> 2][is_thumb];
/* KVM only enters the ABT and UND modes, so only deal with those */
switch(mode) {
case PSR_AA32_MODE_ABT:
__vcpu_write_spsr_abt(vcpu, host_spsr_to_spsr32(spsr));
vcpu_gp_regs(vcpu)->compat_lr_abt = return_address;
break;
case PSR_AA32_MODE_UND:
__vcpu_write_spsr_und(vcpu, host_spsr_to_spsr32(spsr));
vcpu_gp_regs(vcpu)->compat_lr_und = return_address;
break;
}
/* Branch to exception vector */
if (sctlr & (1 << 13))
vect_offset += 0xffff0000;
else /* always have security exceptions */
vect_offset += __vcpu_read_sys_reg(vcpu, VBAR_EL1);
*vcpu_pc(vcpu) = vect_offset;
}
void kvm_inject_exception(struct kvm_vcpu *vcpu)
{
if (vcpu_el1_is_32bit(vcpu)) {
switch (vcpu->arch.flags & KVM_ARM64_EXCEPT_MASK) {
case KVM_ARM64_EXCEPT_AA32_UND:
enter_exception32(vcpu, PSR_AA32_MODE_UND, 4);
break;
case KVM_ARM64_EXCEPT_AA32_IABT:
enter_exception32(vcpu, PSR_AA32_MODE_ABT, 12);
break;
case KVM_ARM64_EXCEPT_AA32_DABT:
enter_exception32(vcpu, PSR_AA32_MODE_ABT, 16);
break;
default:
/* Err... */
break;
}
} else {
switch (vcpu->arch.flags & KVM_ARM64_EXCEPT_MASK) {
case (KVM_ARM64_EXCEPT_AA64_ELx_SYNC |
KVM_ARM64_EXCEPT_AA64_EL1):
enter_exception64(vcpu, PSR_MODE_EL1h, except_type_sync);
break;
default:
/*
* Only EL1_SYNC makes sense so far, EL2_{SYNC,IRQ}
* will be implemented at some point. Everything
* else gets silently ignored.
*/
break;
}
}
}
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