Commit 6e085e0a authored by Will Deacon's avatar Will Deacon Committed by Marc Zyngier
Browse files

arm/arm64: Probe for the presence of KVM hypervisor 



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: default avatarSteven Price <steven.price@arm.com>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
Signed-off-by: default avatarJianyong Wu <jianyong.wu@arm.com>
[maz: move code to its own file, plug it into PSCI]
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201209060932.212364-2-jianyong.wu@arm.com
parent 1e28eed1

arch/arm/include/asm/hypervisor.h

+3 −0
Original line number Diff line number Diff line
@@ -4,4 +4,7 @@ 


#include <asm/xen/hypervisor.h>



void kvm_init_hyp_services(void);

bool kvm_arm_hyp_service_available(u32 func_id);



#endif

arch/arm64/include/asm/hypervisor.h

+3 −0
Original line number Diff line number Diff line
@@ -4,4 +4,7 @@ 


#include <asm/xen/hypervisor.h>



void kvm_init_hyp_services(void);

bool kvm_arm_hyp_service_available(u32 func_id);



#endif

drivers/firmware/psci/psci.c

+2 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 


#include <asm/cpuidle.h>

#include <asm/cputype.h>

#include <asm/hypervisor.h>

#include <asm/system_misc.h>

#include <asm/smp_plat.h>

#include <asm/suspend.h>
@@ -498,6 +499,7 @@ static int __init psci_probe(void) 
		psci_init_cpu_suspend();

		psci_init_system_suspend();

		psci_init_system_reset2();

		kvm_init_hyp_services();

	}



	return 0;

drivers/firmware/smccc/Makefile

+1 −1
Original line number Diff line number Diff line 
# SPDX-License-Identifier: GPL-2.0

#

obj-$(CONFIG_HAVE_ARM_SMCCC_DISCOVERY)	+= smccc.o

obj-$(CONFIG_HAVE_ARM_SMCCC_DISCOVERY)	+= smccc.o kvm_guest.o

obj-$(CONFIG_ARM_SMCCC_SOC_ID)	+= soc_id.o

drivers/firmware/smccc/kvm_guest.c

0 → 100644
+50 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0



#define pr_fmt(fmt) "smccc: KVM: " fmt



#include <linux/arm-smccc.h>

#include <linux/bitmap.h>

#include <linux/kernel.h>

#include <linux/string.h>



#include <asm/hypervisor.h>



static DECLARE_BITMAP(__kvm_arm_hyp_services, ARM_SMCCC_KVM_NUM_FUNCS) __ro_after_init = { };



void __init kvm_init_hyp_services(void)

{

	struct arm_smccc_res res;

	u32 val[4];



	if (arm_smccc_1_1_get_conduit() != SMCCC_CONDUIT_HVC)

		return;



	arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID, &res);

	if (res.a0 != ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_0 ||

	    res.a1 != ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_1 ||

	    res.a2 != ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_2 ||

	    res.a3 != ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_3)

		return;



	memset(&res, 0, sizeof(res));

	arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID, &res);



	val[0] = lower_32_bits(res.a0);

	val[1] = lower_32_bits(res.a1);

	val[2] = lower_32_bits(res.a2);

	val[3] = lower_32_bits(res.a3);



	bitmap_from_arr32(__kvm_arm_hyp_services, val, ARM_SMCCC_KVM_NUM_FUNCS);



	pr_info("hypervisor services detected (0x%08lx 0x%08lx 0x%08lx 0x%08lx)\n",

		 res.a3, res.a2, res.a1, res.a0);

}



bool kvm_arm_hyp_service_available(u32 func_id)

{

	if (func_id >= ARM_SMCCC_KVM_NUM_FUNCS)

		return false;



	return test_bit(func_id, __kvm_arm_hyp_services);

}

EXPORT_SYMBOL_GPL(kvm_arm_hyp_service_available);