From 7f6c295cdfeaa229c360cac9a36e4e595aa902ae Mon Sep 17 00:00:00 2001 From: Alexander Graf Date: Wed, 9 Feb 2022 13:41:35 +0100 Subject: [PATCH] hvf: arm: Handle unknown ID registers as RES0 Recent Linux versions added support to read ID_AA64ISAR2_EL1. On M1, those reads trap into QEMU which handles them as faults. However, AArch64 ID registers should always read as RES0. Let's handle them accordingly. This fixes booting Linux 5.17 guests. Cc: qemu-stable@nongnu.org Reported-by: Ivan Babrou Signed-off-by: Alexander Graf Message-id: 20220209124135.69183-2-agraf@csgraf.de Reviewed-by: Peter Maydell Signed-off-by: Peter Maydell --- target/arm/hvf/hvf.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/target/arm/hvf/hvf.c b/target/arm/hvf/hvf.c index 808c96da8c..4d4ddab348 100644 --- a/target/arm/hvf/hvf.c +++ b/target/arm/hvf/hvf.c @@ -754,6 +754,15 @@ static bool hvf_handle_psci_call(CPUState *cpu) return true; } +static bool is_id_sysreg(uint32_t reg) +{ + return SYSREG_OP0(reg) == 3 && + SYSREG_OP1(reg) == 0 && + SYSREG_CRN(reg) == 0 && + SYSREG_CRM(reg) >= 1 && + SYSREG_CRM(reg) < 8; +} + static int hvf_sysreg_read(CPUState *cpu, uint32_t reg, uint32_t rt) { ARMCPU *arm_cpu = ARM_CPU(cpu); @@ -806,6 +815,11 @@ static int hvf_sysreg_read(CPUState *cpu, uint32_t reg, uint32_t rt) /* Dummy register */ break; default: + if (is_id_sysreg(reg)) { + /* ID system registers read as RES0 */ + val = 0; + break; + } cpu_synchronize_state(cpu); trace_hvf_unhandled_sysreg_read(env->pc, reg, SYSREG_OP0(reg), -- 2.39.2