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Although the SMCCC specification provides some limited functionality for describing the presence of hypervisor and firmware services, this is generally applicable only to functions designated as "Arm Architecture Service Functions" and no portable discovery mechanism is provided for standard hypervisor services, despite having a designated range of function identifiers reserved by the specification. In an attempt to avoid the need for additional firmware changes every time a new function is added, introduce a UID to identify the service provider as being compatible with KVM. Once this has been established, additional services can be discovered via a feature bitmap. Reviewed-by: Steven Price <steven.price@arm.com> Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Jianyong Wu <jianyong.wu@arm.com> [maz: move code to its own file, plug it into PSCI] Signed-off-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20201209060932.212364-2-jianyong.wu@arm.com
50 lines
1.4 KiB
C
50 lines
1.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#define pr_fmt(fmt) "smccc: KVM: " fmt
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#include <linux/arm-smccc.h>
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#include <linux/bitmap.h>
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#include <linux/kernel.h>
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#include <linux/string.h>
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#include <asm/hypervisor.h>
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static DECLARE_BITMAP(__kvm_arm_hyp_services, ARM_SMCCC_KVM_NUM_FUNCS) __ro_after_init = { };
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void __init kvm_init_hyp_services(void)
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{
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struct arm_smccc_res res;
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u32 val[4];
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if (arm_smccc_1_1_get_conduit() != SMCCC_CONDUIT_HVC)
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return;
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arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID, &res);
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if (res.a0 != ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_0 ||
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res.a1 != ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_1 ||
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res.a2 != ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_2 ||
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res.a3 != ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_3)
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return;
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memset(&res, 0, sizeof(res));
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arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID, &res);
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val[0] = lower_32_bits(res.a0);
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val[1] = lower_32_bits(res.a1);
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val[2] = lower_32_bits(res.a2);
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val[3] = lower_32_bits(res.a3);
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bitmap_from_arr32(__kvm_arm_hyp_services, val, ARM_SMCCC_KVM_NUM_FUNCS);
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pr_info("hypervisor services detected (0x%08lx 0x%08lx 0x%08lx 0x%08lx)\n",
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res.a3, res.a2, res.a1, res.a0);
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}
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bool kvm_arm_hyp_service_available(u32 func_id)
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{
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if (func_id >= ARM_SMCCC_KVM_NUM_FUNCS)
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return false;
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return test_bit(func_id, __kvm_arm_hyp_services);
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}
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EXPORT_SYMBOL_GPL(kvm_arm_hyp_service_available);
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