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arm64: Add workaround for Arm Cortex-A77 erratum 1508412 

On Cortex-A77 r0p0 and r1p0, a sequence of a non-cacheable or device load
and a store exclusive or PAR_EL1 read can cause a deadlock.

The workaround requires a DMB SY before and after a PAR_EL1 register
read. In addition, it's possible an interrupt (doing a device read) or
KVM guest exit could be taken between the DMB and PAR read, so we
also need a DMB before returning from interrupt and before returning to
a guest.

A deadlock is still possible with the workaround as KVM guests must also
have the workaround. IOW, a malicious guest can deadlock an affected
systems.

This workaround also depends on a firmware counterpart to enable the h/w
to insert DMB SY after load and store exclusive instructions. See the
errata document SDEN-1152370 v10 [1] for more information.

[1] https://static.docs.arm.com/101992/0010/Arm_Cortex_A77_MP074_Software_Developer_Errata_Notice_v10.pdf

Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Julien Thierry <julien.thierry.kdev@gmail.com>
Cc: kvmarm@lists.cs.columbia.edu
Link: https://lore.kernel.org/r/20201028182839.166037-2-robh@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Rob Herring 2020-10-28 13:28:39 -05:00 committed by Will Deacon
parent 8a6b88e662
commit 96d389ca10
13 changed files with 66 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
Documentation/arm64/silicon-errata.rst
View File

@ -90,6 +90,8 @@ stable kernels.
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A76 | #1463225 | ARM64_ERRATUM_1463225 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A77 | #1508412 | ARM64_ERRATUM_1508412 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Neoverse-N1 | #1188873,1418040| ARM64_ERRATUM_1418040 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Neoverse-N1 | #1349291 | N/A |

20
arch/arm64/Kconfig
View File

@ -636,6 +636,26 @@ config ARM64_ERRATUM_1542419
If unsure, say Y.
config ARM64_ERRATUM_1508412
bool "Cortex-A77: 1508412: workaround deadlock on sequence of NC/Device load and store exclusive or PAR read"
default y
help
This option adds a workaround for Arm Cortex-A77 erratum 1508412.
Affected Cortex-A77 cores (r0p0, r1p0) could deadlock on a sequence
of a store-exclusive or read of PAR_EL1 and a load with device or
non-cacheable memory attributes. The workaround depends on a firmware
counterpart.
KVM guests must also have the workaround implemented or they can
deadlock the system.
Work around the issue by inserting DMB SY barriers around PAR_EL1
register reads and warning KVM users. The DMB barrier is sufficient
to prevent a speculative PAR_EL1 read.
If unsure, say Y.
config CAVIUM_ERRATUM_22375
bool "Cavium erratum 22375, 24313"
default y

3
arch/arm64/include/asm/cpucaps.h
View File

@ -65,7 +65,8 @@
#define ARM64_HAS_ARMv8_4_TTL 55
#define ARM64_HAS_TLB_RANGE 56
#define ARM64_MTE 57
#define ARM64_WORKAROUND_1508412 58
#define ARM64_NCAPS 58
#define ARM64_NCAPS 59
#endif /* __ASM_CPUCAPS_H */

9
arch/arm64/include/asm/sysreg.h
View File

@ -1007,6 +1007,7 @@
#include <linux/build_bug.h>
#include <linux/types.h>
#include <asm/alternative.h>
#define __DEFINE_MRS_MSR_S_REGNUM \
" .irp num,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30\n" \
@ -1095,6 +1096,14 @@
write_sysreg_s(__scs_new, sysreg); \
} while (0)
#define read_sysreg_par() ({ \
u64 par; \
asm(ALTERNATIVE("nop", "dmb sy", ARM64_WORKAROUND_1508412)); \
par = read_sysreg(par_el1); \
asm(ALTERNATIVE("nop", "dmb sy", ARM64_WORKAROUND_1508412)); \
par; \
})
#endif
#endif /* __ASM_SYSREG_H */

10
arch/arm64/kernel/cpu_errata.c
View File

@ -522,6 +522,16 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
.matches = has_neoverse_n1_erratum_1542419,
.cpu_enable = cpu_enable_trap_ctr_access,
},
#endif
#ifdef CONFIG_ARM64_ERRATUM_1508412
{
/* we depend on the firmware portion for correctness */
.desc = "ARM erratum 1508412 (kernel portion)",
.capability = ARM64_WORKAROUND_1508412,
ERRATA_MIDR_RANGE(MIDR_CORTEX_A77,
0, 0,
1, 0),
},
#endif
{
}

3
arch/arm64/kernel/entry.S
View File

@ -365,6 +365,9 @@ alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0
br x30
#endif
.else
/* Ensure any device/NC reads complete */
alternative_insn nop, "dmb sy", ARM64_WORKAROUND_1508412
eret
.endif
sb

3
arch/arm64/kvm/arm.c
View File

@ -1719,7 +1719,8 @@ int kvm_arch_init(void *opaque)
return -ENODEV;
}
if (cpus_have_final_cap(ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE))
if (cpus_have_final_cap(ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE) ||
cpus_have_final_cap(ARM64_WORKAROUND_1508412))
kvm_info("Guests without required CPU erratum workarounds can deadlock system!\n" \
"Only trusted guests should be used on this system.\n");

21
arch/arm64/kvm/hyp/include/hyp/switch.h
View File

@ -140,9 +140,9 @@ static inline bool __translate_far_to_hpfar(u64 far, u64 *hpfar)
* We do need to save/restore PAR_EL1 though, as we haven't
* saved the guest context yet, and we may return early...
*/
par = read_sysreg(par_el1);
par = read_sysreg_par();
if (!__kvm_at("s1e1r", far))
tmp = read_sysreg(par_el1);
tmp = read_sysreg_par();
else
tmp = SYS_PAR_EL1_F; /* back to the guest */
write_sysreg(par, par_el1);
@ -421,7 +421,7 @@ static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
if (cpus_have_final_cap(ARM64_WORKAROUND_CAVIUM_TX2_219_TVM) &&
kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_SYS64 &&
handle_tx2_tvm(vcpu))
return true;
goto guest;
/*
* We trap the first access to the FP/SIMD to save the host context
@ -431,13 +431,13 @@ static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
* Similarly for trapped SVE accesses.
*/
if (__hyp_handle_fpsimd(vcpu))
return true;
goto guest;
if (__hyp_handle_ptrauth(vcpu))
return true;
goto guest;
if (!__populate_fault_info(vcpu))
return true;
goto guest;
if (static_branch_unlikely(&vgic_v2_cpuif_trap)) {
bool valid;
@ -452,7 +452,7 @@ static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
int ret = __vgic_v2_perform_cpuif_access(vcpu);
if (ret == 1)
return true;
goto guest;
/* Promote an illegal access to an SError.*/
if (ret == -1)
@ -468,12 +468,17 @@ static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
int ret = __vgic_v3_perform_cpuif_access(vcpu);
if (ret == 1)
return true;
goto guest;
}
exit:
/* Return to the host kernel and handle the exit */
return false;
guest:
/* Re-enter the guest */
asm(ALTERNATIVE("nop", "dmb sy", ARM64_WORKAROUND_1508412));
return true;
}
static inline void __kvm_unexpected_el2_exception(void)

2
arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h
View File

@ -43,7 +43,7 @@ static inline void __sysreg_save_el1_state(struct kvm_cpu_context *ctxt)
ctxt_sys_reg(ctxt, CONTEXTIDR_EL1) = read_sysreg_el1(SYS_CONTEXTIDR);
ctxt_sys_reg(ctxt, AMAIR_EL1) = read_sysreg_el1(SYS_AMAIR);
ctxt_sys_reg(ctxt, CNTKCTL_EL1) = read_sysreg_el1(SYS_CNTKCTL);
ctxt_sys_reg(ctxt, PAR_EL1) = read_sysreg(par_el1);
ctxt_sys_reg(ctxt, PAR_EL1) = read_sysreg_par();
ctxt_sys_reg(ctxt, TPIDR_EL1) = read_sysreg(tpidr_el1);
ctxt_sys_reg(ctxt, SP_EL1) = read_sysreg(sp_el1);

2
arch/arm64/kvm/hyp/nvhe/switch.c
View File

@ -250,7 +250,7 @@ void __noreturn hyp_panic(void)
{
u64 spsr = read_sysreg_el2(SYS_SPSR);
u64 elr = read_sysreg_el2(SYS_ELR);
u64 par = read_sysreg(par_el1);
u64 par = read_sysreg_par();
bool restore_host = true;
struct kvm_cpu_context *host_ctxt;
struct kvm_vcpu *vcpu;

2
arch/arm64/kvm/hyp/vhe/switch.c
View File

@ -215,7 +215,7 @@ void __noreturn hyp_panic(void)
{
u64 spsr = read_sysreg_el2(SYS_SPSR);
u64 elr = read_sysreg_el2(SYS_ELR);
u64 par = read_sysreg(par_el1);
u64 par = read_sysreg_par();
__hyp_call_panic(spsr, elr, par);
unreachable();

2
arch/arm64/kvm/sys_regs.c
View File

@ -95,7 +95,7 @@ static bool __vcpu_read_sys_reg_from_cpu(int reg, u64 *val)
case AMAIR_EL1: *val = read_sysreg_s(SYS_AMAIR_EL12); break;
case CNTKCTL_EL1: *val = read_sysreg_s(SYS_CNTKCTL_EL12); break;
case ELR_EL1: *val = read_sysreg_s(SYS_ELR_EL12); break;
case PAR_EL1: *val = read_sysreg_s(SYS_PAR_EL1); break;
case PAR_EL1: *val = read_sysreg_par(); break;
case DACR32_EL2: *val = read_sysreg_s(SYS_DACR32_EL2); break;
case IFSR32_EL2: *val = read_sysreg_s(SYS_IFSR32_EL2); break;
case DBGVCR32_EL2: *val = read_sysreg_s(SYS_DBGVCR32_EL2); break;

2
arch/arm64/mm/fault.c
View File

@ -262,7 +262,7 @@ static bool __kprobes is_spurious_el1_translation_fault(unsigned long addr,
local_irq_save(flags);
asm volatile("at s1e1r, %0" :: "r" (addr));
isb();
par = read_sysreg(par_el1);
par = read_sysreg_par();
local_irq_restore(flags);
/*