From 77077a83006c3c9bdca496727f1735a3c5c5355d Mon Sep 17 00:00:00 2001 From: Jan Kiszka Date: Fri, 6 Oct 2017 16:46:47 +0100 Subject: [PATCH] arm: Fix SMC reporting to EL2 when QEMU provides PSCI This properly forwards SMC events to EL2 when PSCI is provided by QEMU itself and, thus, ARM_FEATURE_EL3 is off. Found and tested with the Jailhouse hypervisor. Solution based on suggestions by Peter Maydell. Signed-off-by: Jan Kiszka Message-id: 4f243068-aaea-776f-d18f-f9e05e7be9cd@siemens.com Reviewed-by: Peter Maydell Signed-off-by: Peter Maydell --- target/arm/helper.c | 9 ++++++++- target/arm/op_helper.c | 27 +++++++++++++++++---------- 2 files changed, 25 insertions(+), 11 deletions(-) diff --git a/target/arm/helper.c b/target/arm/helper.c index 8be78ea2f8..0b9c9fded6 100644 --- a/target/arm/helper.c +++ b/target/arm/helper.c @@ -3717,7 +3717,14 @@ static void hcr_write(CPUARMState *env, const ARMCPRegInfo *ri, uint64_t value) if (arm_feature(env, ARM_FEATURE_EL3)) { valid_mask &= ~HCR_HCD; - } else { + } else if (cpu->psci_conduit != QEMU_PSCI_CONDUIT_SMC) { + /* Architecturally HCR.TSC is RES0 if EL3 is not implemented. + * However, if we're using the SMC PSCI conduit then QEMU is + * effectively acting like EL3 firmware and so the guest at + * EL2 should retain the ability to prevent EL1 from being + * able to make SMC calls into the ersatz firmware, so in + * that case HCR.TSC should be read/write. + */ valid_mask &= ~HCR_TSC; } diff --git a/target/arm/op_helper.c b/target/arm/op_helper.c index 6a60464ab9..3914145709 100644 --- a/target/arm/op_helper.c +++ b/target/arm/op_helper.c @@ -953,22 +953,29 @@ void HELPER(pre_smc)(CPUARMState *env, uint32_t syndrome) */ bool undef = arm_feature(env, ARM_FEATURE_AARCH64) ? smd : smd && !secure; - if (arm_is_psci_call(cpu, EXCP_SMC)) { - /* If PSCI is enabled and this looks like a valid PSCI call then - * that overrides the architecturally mandated SMC behaviour. + if (!arm_feature(env, ARM_FEATURE_EL3) && + cpu->psci_conduit != QEMU_PSCI_CONDUIT_SMC) { + /* If we have no EL3 then SMC always UNDEFs and can't be + * trapped to EL2. PSCI-via-SMC is a sort of ersatz EL3 + * firmware within QEMU, and we want an EL2 guest to be able + * to forbid its EL1 from making PSCI calls into QEMU's + * "firmware" via HCR.TSC, so for these purposes treat + * PSCI-via-SMC as implying an EL3. */ - return; - } - - if (!arm_feature(env, ARM_FEATURE_EL3)) { - /* If we have no EL3 then SMC always UNDEFs */ undef = true; } else if (!secure && cur_el == 1 && (env->cp15.hcr_el2 & HCR_TSC)) { - /* In NS EL1, HCR controlled routing to EL2 has priority over SMD. */ + /* In NS EL1, HCR controlled routing to EL2 has priority over SMD. + * We also want an EL2 guest to be able to forbid its EL1 from + * making PSCI calls into QEMU's "firmware" via HCR.TSC. + */ raise_exception(env, EXCP_HYP_TRAP, syndrome, 2); } - if (undef) { + /* If PSCI is enabled and this looks like a valid PSCI call then + * suppress the UNDEF -- we'll catch the SMC exception and + * implement the PSCI call behaviour there. + */ + if (undef && !arm_is_psci_call(cpu, EXCP_SMC)) { raise_exception(env, EXCP_UDEF, syn_uncategorized(), exception_target_el(env)); }