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android_kernel_xiaomi_sm8450/arch/arm64/include/asm/kvm_emulate.h
Marc Zyngier c47883105c KVM: arm64: Fix S1PTW handling on RO memslots 
commit 406504c7b0405d74d74c15a667cd4c4620c3e7a9 upstream.

A recent development on the EFI front has resulted in guests having
their page tables baked in the firmware binary, and mapped into the
IPA space as part of a read-only memslot. Not only is this legitimate,
but it also results in added security, so thumbs up.

It is possible to take an S1PTW translation fault if the S1 PTs are
unmapped at stage-2. However, KVM unconditionally treats S1PTW as a
write to correctly handle hardware AF/DB updates to the S1 PTs.
Furthermore, KVM injects an exception into the guest for S1PTW writes.
In the aforementioned case this results in the guest taking an abort
it won't recover from, as the S1 PTs mapping the vectors suffer from
the same problem.

So clearly our handling is... wrong.

Instead, switch to a two-pronged approach:

- On S1PTW translation fault, handle the fault as a read

- On S1PTW permission fault, handle the fault as a write

This is of no consequence to SW that *writes* to its PTs (the write
will trigger a non-S1PTW fault), and SW that uses RO PTs will not
use HW-assisted AF/DB anyway, as that'd be wrong.

Only in the case described in c4ad98e4b7 ("KVM: arm64: Assume write
fault on S1PTW permission fault on instruction fetch") do we end-up
with two back-to-back faults (page being evicted and faulted back).
I don't think this is a case worth optimising for.

Fixes: c4ad98e4b7 ("KVM: arm64: Assume write fault on S1PTW permission fault on instruction fetch")
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Regression-tested-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-01-18 11:44:52 +01:00

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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2012,2013 - ARM Ltd
* Author: Marc Zyngier <marc.zyngier@arm.com>
*
* Derived from arch/arm/include/kvm_emulate.h
* Copyright (C) 2012 - Virtual Open Systems and Columbia University
* Author: Christoffer Dall <c.dall@virtualopensystems.com>
*/
#ifndef __ARM64_KVM_EMULATE_H__
#define __ARM64_KVM_EMULATE_H__
#include <linux/kvm_host.h>
#include <asm/debug-monitors.h>
#include <asm/esr.h>
#include <asm/kvm_arm.h>
#include <asm/kvm_hyp.h>
#include <asm/ptrace.h>
#include <asm/cputype.h>
#include <asm/virt.h>
unsigned long *vcpu_reg32(const struct kvm_vcpu *vcpu, u8 reg_num);
unsigned long vcpu_read_spsr32(const struct kvm_vcpu *vcpu);
void vcpu_write_spsr32(struct kvm_vcpu *vcpu, unsigned long v);
bool kvm_condition_valid32(const struct kvm_vcpu *vcpu);
void kvm_skip_instr32(struct kvm_vcpu *vcpu, bool is_wide_instr);
void kvm_inject_undefined(struct kvm_vcpu *vcpu);
void kvm_inject_vabt(struct kvm_vcpu *vcpu);
void kvm_inject_dabt(struct kvm_vcpu *vcpu, unsigned long addr);
void kvm_inject_pabt(struct kvm_vcpu *vcpu, unsigned long addr);
void kvm_inject_undef32(struct kvm_vcpu *vcpu);
void kvm_inject_dabt32(struct kvm_vcpu *vcpu, unsigned long addr);
void kvm_inject_pabt32(struct kvm_vcpu *vcpu, unsigned long addr);
static __always_inline bool vcpu_el1_is_32bit(struct kvm_vcpu *vcpu)
{
return !(vcpu->arch.hcr_el2 & HCR_RW);
}
static inline void vcpu_reset_hcr(struct kvm_vcpu *vcpu)
{
vcpu->arch.hcr_el2 = HCR_GUEST_FLAGS;
if (is_kernel_in_hyp_mode())
vcpu->arch.hcr_el2 |= HCR_E2H;
if (cpus_have_const_cap(ARM64_HAS_RAS_EXTN)) {
/* route synchronous external abort exceptions to EL2 */
vcpu->arch.hcr_el2 |= HCR_TEA;
/* trap error record accesses */
vcpu->arch.hcr_el2 |= HCR_TERR;
}
if (cpus_have_const_cap(ARM64_HAS_STAGE2_FWB)) {
vcpu->arch.hcr_el2 |= HCR_FWB;
} else {
/*
* For non-FWB CPUs, we trap VM ops (HCR_EL2.TVM) until M+C
* get set in SCTLR_EL1 such that we can detect when the guest
* MMU gets turned on and do the necessary cache maintenance
* then.
*/
vcpu->arch.hcr_el2 |= HCR_TVM;
}
if (test_bit(KVM_ARM_VCPU_EL1_32BIT, vcpu->arch.features))
vcpu->arch.hcr_el2 &= ~HCR_RW;
/*
* TID3: trap feature register accesses that we virtualise.
* For now this is conditional, since no AArch32 feature regs
* are currently virtualised.
*/
if (!vcpu_el1_is_32bit(vcpu))
vcpu->arch.hcr_el2 |= HCR_TID3;
if (cpus_have_const_cap(ARM64_MISMATCHED_CACHE_TYPE) ||
vcpu_el1_is_32bit(vcpu))
vcpu->arch.hcr_el2 |= HCR_TID2;
}
static inline unsigned long *vcpu_hcr(struct kvm_vcpu *vcpu)
{
return (unsigned long *)&vcpu->arch.hcr_el2;
}
static inline void vcpu_clear_wfx_traps(struct kvm_vcpu *vcpu)
{
vcpu->arch.hcr_el2 &= ~HCR_TWE;
if (atomic_read(&vcpu->arch.vgic_cpu.vgic_v3.its_vpe.vlpi_count) ||
vcpu->kvm->arch.vgic.nassgireq)
vcpu->arch.hcr_el2 &= ~HCR_TWI;
else
vcpu->arch.hcr_el2 |= HCR_TWI;
}
static inline void vcpu_set_wfx_traps(struct kvm_vcpu *vcpu)
{
vcpu->arch.hcr_el2 |= HCR_TWE;
vcpu->arch.hcr_el2 |= HCR_TWI;
}
static inline void vcpu_ptrauth_enable(struct kvm_vcpu *vcpu)
{
vcpu->arch.hcr_el2 |= (HCR_API | HCR_APK);
}
static inline void vcpu_ptrauth_disable(struct kvm_vcpu *vcpu)
{
vcpu->arch.hcr_el2 &= ~(HCR_API | HCR_APK);
}
static inline unsigned long vcpu_get_vsesr(struct kvm_vcpu *vcpu)
{
return vcpu->arch.vsesr_el2;
}
static inline void vcpu_set_vsesr(struct kvm_vcpu *vcpu, u64 vsesr)
{
vcpu->arch.vsesr_el2 = vsesr;
}
static __always_inline unsigned long *vcpu_pc(const struct kvm_vcpu *vcpu)
{
return (unsigned long *)&vcpu_gp_regs(vcpu)->pc;
}
static __always_inline unsigned long *vcpu_cpsr(const struct kvm_vcpu *vcpu)
{
return (unsigned long *)&vcpu_gp_regs(vcpu)->pstate;
}
static __always_inline bool vcpu_mode_is_32bit(const struct kvm_vcpu *vcpu)
{
return !!(*vcpu_cpsr(vcpu) & PSR_MODE32_BIT);
}
static __always_inline bool kvm_condition_valid(const struct kvm_vcpu *vcpu)
{
if (vcpu_mode_is_32bit(vcpu))
return kvm_condition_valid32(vcpu);
return true;
}
static inline void vcpu_set_thumb(struct kvm_vcpu *vcpu)
{
*vcpu_cpsr(vcpu) |= PSR_AA32_T_BIT;
}
/*
* vcpu_get_reg and vcpu_set_reg should always be passed a register number
* coming from a read of ESR_EL2. Otherwise, it may give the wrong result on
* AArch32 with banked registers.
*/
static __always_inline unsigned long vcpu_get_reg(const struct kvm_vcpu *vcpu,
u8 reg_num)
{
return (reg_num == 31) ? 0 : vcpu_gp_regs(vcpu)->regs[reg_num];
}
static __always_inline void vcpu_set_reg(struct kvm_vcpu *vcpu, u8 reg_num,
unsigned long val)
{
if (reg_num != 31)
vcpu_gp_regs(vcpu)->regs[reg_num] = val;
}
static inline unsigned long vcpu_read_spsr(const struct kvm_vcpu *vcpu)
{
if (vcpu_mode_is_32bit(vcpu))
return vcpu_read_spsr32(vcpu);
if (vcpu->arch.sysregs_loaded_on_cpu)
return read_sysreg_el1(SYS_SPSR);
else
return __vcpu_sys_reg(vcpu, SPSR_EL1);
}
static inline void vcpu_write_spsr(struct kvm_vcpu *vcpu, unsigned long v)
{
if (vcpu_mode_is_32bit(vcpu)) {
vcpu_write_spsr32(vcpu, v);
return;
}
if (vcpu->arch.sysregs_loaded_on_cpu)
write_sysreg_el1(v, SYS_SPSR);
else
__vcpu_sys_reg(vcpu, SPSR_EL1) = v;
}
/*
* The layout of SPSR for an AArch32 state is different when observed from an
* AArch64 SPSR_ELx or an AArch32 SPSR_*. This function generates the AArch32
* view given an AArch64 view.
*
* In ARM DDI 0487E.a see:
*
* - The AArch64 view (SPSR_EL2) in section C5.2.18, page C5-426
* - The AArch32 view (SPSR_abt) in section G8.2.126, page G8-6256
* - The AArch32 view (SPSR_und) in section G8.2.132, page G8-6280
*
* Which show the following differences:
*
* | Bit | AA64 | AA32 | Notes |
* +-----+------+------+-----------------------------|
* | 24 | DIT | J | J is RES0 in ARMv8 |
* | 21 | SS | DIT | SS doesn't exist in AArch32 |
*
* ... and all other bits are (currently) common.
*/
static inline unsigned long host_spsr_to_spsr32(unsigned long spsr)
{
const unsigned long overlap = BIT(24) | BIT(21);
unsigned long dit = !!(spsr & PSR_AA32_DIT_BIT);
spsr &= ~overlap;
spsr |= dit << 21;
return spsr;
}
static inline bool vcpu_mode_priv(const struct kvm_vcpu *vcpu)
{
u32 mode;
if (vcpu_mode_is_32bit(vcpu)) {
mode = *vcpu_cpsr(vcpu) & PSR_AA32_MODE_MASK;
return mode > PSR_AA32_MODE_USR;
}
mode = *vcpu_cpsr(vcpu) & PSR_MODE_MASK;
return mode != PSR_MODE_EL0t;
}
static __always_inline u32 kvm_vcpu_get_esr(const struct kvm_vcpu *vcpu)
{
return vcpu->arch.fault.esr_el2;
}
static __always_inline int kvm_vcpu_get_condition(const struct kvm_vcpu *vcpu)
{
u32 esr = kvm_vcpu_get_esr(vcpu);
if (esr & ESR_ELx_CV)
return (esr & ESR_ELx_COND_MASK) >> ESR_ELx_COND_SHIFT;
return -1;
}
static __always_inline unsigned long kvm_vcpu_get_hfar(const struct kvm_vcpu *vcpu)
{
return vcpu->arch.fault.far_el2;
}
static __always_inline phys_addr_t kvm_vcpu_get_fault_ipa(const struct kvm_vcpu *vcpu)
{
return ((phys_addr_t)vcpu->arch.fault.hpfar_el2 & HPFAR_MASK) << 8;
}
static inline u64 kvm_vcpu_get_disr(const struct kvm_vcpu *vcpu)
{
return vcpu->arch.fault.disr_el1;
}
static inline u32 kvm_vcpu_hvc_get_imm(const struct kvm_vcpu *vcpu)
{
return kvm_vcpu_get_esr(vcpu) & ESR_ELx_xVC_IMM_MASK;
}
static __always_inline bool kvm_vcpu_dabt_isvalid(const struct kvm_vcpu *vcpu)
{
return !!(kvm_vcpu_get_esr(vcpu) & ESR_ELx_ISV);
}
static inline unsigned long kvm_vcpu_dabt_iss_nisv_sanitized(const struct kvm_vcpu *vcpu)
{
return kvm_vcpu_get_esr(vcpu) & (ESR_ELx_CM | ESR_ELx_WNR | ESR_ELx_FSC);
}
static inline bool kvm_vcpu_dabt_issext(const struct kvm_vcpu *vcpu)
{
return !!(kvm_vcpu_get_esr(vcpu) & ESR_ELx_SSE);
}
static inline bool kvm_vcpu_dabt_issf(const struct kvm_vcpu *vcpu)
{
return !!(kvm_vcpu_get_esr(vcpu) & ESR_ELx_SF);
}
static __always_inline int kvm_vcpu_dabt_get_rd(const struct kvm_vcpu *vcpu)
{
return (kvm_vcpu_get_esr(vcpu) & ESR_ELx_SRT_MASK) >> ESR_ELx_SRT_SHIFT;
}
static __always_inline bool kvm_vcpu_abt_iss1tw(const struct kvm_vcpu *vcpu)
{
return !!(kvm_vcpu_get_esr(vcpu) & ESR_ELx_S1PTW);
}
/* Always check for S1PTW *before* using this. */
static __always_inline bool kvm_vcpu_dabt_iswrite(const struct kvm_vcpu *vcpu)
{
return kvm_vcpu_get_esr(vcpu) & ESR_ELx_WNR;
}
static inline bool kvm_vcpu_dabt_is_cm(const struct kvm_vcpu *vcpu)
{
return !!(kvm_vcpu_get_esr(vcpu) & ESR_ELx_CM);
}
static __always_inline unsigned int kvm_vcpu_dabt_get_as(const struct kvm_vcpu *vcpu)
{
return 1 << ((kvm_vcpu_get_esr(vcpu) & ESR_ELx_SAS) >> ESR_ELx_SAS_SHIFT);
}
/* This one is not specific to Data Abort */
static __always_inline bool kvm_vcpu_trap_il_is32bit(const struct kvm_vcpu *vcpu)
{
return !!(kvm_vcpu_get_esr(vcpu) & ESR_ELx_IL);
}
static __always_inline u8 kvm_vcpu_trap_get_class(const struct kvm_vcpu *vcpu)
{
return ESR_ELx_EC(kvm_vcpu_get_esr(vcpu));
}
static inline bool kvm_vcpu_trap_is_iabt(const struct kvm_vcpu *vcpu)
{
return kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_IABT_LOW;
}
static inline bool kvm_vcpu_trap_is_exec_fault(const struct kvm_vcpu *vcpu)
{
return kvm_vcpu_trap_is_iabt(vcpu) && !kvm_vcpu_abt_iss1tw(vcpu);
}
static __always_inline u8 kvm_vcpu_trap_get_fault(const struct kvm_vcpu *vcpu)
{
return kvm_vcpu_get_esr(vcpu) & ESR_ELx_FSC;
}
static __always_inline u8 kvm_vcpu_trap_get_fault_type(const struct kvm_vcpu *vcpu)
{
return kvm_vcpu_get_esr(vcpu) & ESR_ELx_FSC_TYPE;
}
static __always_inline u8 kvm_vcpu_trap_get_fault_level(const struct kvm_vcpu *vcpu)
{
return kvm_vcpu_get_esr(vcpu) & ESR_ELx_FSC_LEVEL;
}
static __always_inline bool kvm_vcpu_abt_issea(const struct kvm_vcpu *vcpu)
{
switch (kvm_vcpu_trap_get_fault(vcpu)) {
case FSC_SEA:
case FSC_SEA_TTW0:
case FSC_SEA_TTW1:
case FSC_SEA_TTW2:
case FSC_SEA_TTW3:
case FSC_SECC:
case FSC_SECC_TTW0:
case FSC_SECC_TTW1:
case FSC_SECC_TTW2:
case FSC_SECC_TTW3:
return true;
default:
return false;
}
}
static __always_inline int kvm_vcpu_sys_get_rt(struct kvm_vcpu *vcpu)
{
u32 esr = kvm_vcpu_get_esr(vcpu);
return ESR_ELx_SYS64_ISS_RT(esr);
}
static inline bool kvm_is_write_fault(struct kvm_vcpu *vcpu)
{
if (kvm_vcpu_abt_iss1tw(vcpu)) {
/*
* Only a permission fault on a S1PTW should be
* considered as a write. Otherwise, page tables baked
* in a read-only memslot will result in an exception
* being delivered in the guest.
*
* The drawback is that we end-up faulting twice if the
* guest is using any of HW AF/DB: a translation fault
* to map the page containing the PT (read only at
* first), then a permission fault to allow the flags
* to be set.
*/
switch (kvm_vcpu_trap_get_fault_type(vcpu)) {
case ESR_ELx_FSC_PERM:
return true;
default:
return false;
}
}
if (kvm_vcpu_trap_is_iabt(vcpu))
return false;
return kvm_vcpu_dabt_iswrite(vcpu);
}
static inline unsigned long kvm_vcpu_get_mpidr_aff(struct kvm_vcpu *vcpu)
{
return vcpu_read_sys_reg(vcpu, MPIDR_EL1) & MPIDR_HWID_BITMASK;
}
static inline void kvm_vcpu_set_be(struct kvm_vcpu *vcpu)
{
if (vcpu_mode_is_32bit(vcpu)) {
*vcpu_cpsr(vcpu) |= PSR_AA32_E_BIT;
} else {
u64 sctlr = vcpu_read_sys_reg(vcpu, SCTLR_EL1);
sctlr |= (1 << 25);
vcpu_write_sys_reg(vcpu, sctlr, SCTLR_EL1);
}
}
static inline bool kvm_vcpu_is_be(struct kvm_vcpu *vcpu)
{
if (vcpu_mode_is_32bit(vcpu))
return !!(*vcpu_cpsr(vcpu) & PSR_AA32_E_BIT);
return !!(vcpu_read_sys_reg(vcpu, SCTLR_EL1) & (1 << 25));
}
static inline unsigned long vcpu_data_guest_to_host(struct kvm_vcpu *vcpu,
unsigned long data,
unsigned int len)
{
if (kvm_vcpu_is_be(vcpu)) {
switch (len) {
case 1:
return data & 0xff;
case 2:
return be16_to_cpu(data & 0xffff);
case 4:
return be32_to_cpu(data & 0xffffffff);
default:
return be64_to_cpu(data);
}
} else {
switch (len) {
case 1:
return data & 0xff;
case 2:
return le16_to_cpu(data & 0xffff);
case 4:
return le32_to_cpu(data & 0xffffffff);
default:
return le64_to_cpu(data);
}
}
return data; /* Leave LE untouched */
}
static inline unsigned long vcpu_data_host_to_guest(struct kvm_vcpu *vcpu,
unsigned long data,
unsigned int len)
{
if (kvm_vcpu_is_be(vcpu)) {
switch (len) {
case 1:
return data & 0xff;
case 2:
return cpu_to_be16(data & 0xffff);
case 4:
return cpu_to_be32(data & 0xffffffff);
default:
return cpu_to_be64(data);
}
} else {
switch (len) {
case 1:
return data & 0xff;
case 2:
return cpu_to_le16(data & 0xffff);
case 4:
return cpu_to_le32(data & 0xffffffff);
default:
return cpu_to_le64(data);
}
}
return data; /* Leave LE untouched */
}
static __always_inline void kvm_skip_instr(struct kvm_vcpu *vcpu, bool is_wide_instr)
{
if (vcpu_mode_is_32bit(vcpu)) {
kvm_skip_instr32(vcpu, is_wide_instr);
} else {
*vcpu_pc(vcpu) += 4;
*vcpu_cpsr(vcpu) &= ~PSR_BTYPE_MASK;
}
/* advance the singlestep state machine */
*vcpu_cpsr(vcpu) &= ~DBG_SPSR_SS;
}
/*
* Skip an instruction which has been emulated at hyp while most guest sysregs
* are live.
*/
static __always_inline void __kvm_skip_instr(struct kvm_vcpu *vcpu)
{
*vcpu_pc(vcpu) = read_sysreg_el2(SYS_ELR);
vcpu_gp_regs(vcpu)->pstate = read_sysreg_el2(SYS_SPSR);
kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
write_sysreg_el2(vcpu_gp_regs(vcpu)->pstate, SYS_SPSR);
write_sysreg_el2(*vcpu_pc(vcpu), SYS_ELR);
}
static inline bool vcpu_has_feature(struct kvm_vcpu *vcpu, int feature)
{
return test_bit(feature, vcpu->arch.features);
}
#endif /* __ARM64_KVM_EMULATE_H__ */
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