Commit 29e8910a authored by Marc Zyngier's avatar Marc Zyngier Committed by Will Deacon
Browse files

KVM: arm64: Simplify handling of ARCH_WORKAROUND_2 



Owing to the fact that the host kernel is always mitigated, we can
drastically simplify the WA2 handling by keeping the mitigation
state ON when entering the guest. This means the guest is either
unaffected or not mitigated.

This results in a nice simplification of the mitigation space,
and the removal of a lot of code that was never really used anyway.

Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent c2876207

arch/arm64/include/asm/kvm_asm.h

+0 −3
Original line number Diff line number Diff line
@@ -9,9 +9,6 @@ 


#include <asm/virt.h>



#define	VCPU_WORKAROUND_2_FLAG_SHIFT	0

#define	VCPU_WORKAROUND_2_FLAG		(_AC(1, UL) << VCPU_WORKAROUND_2_FLAG_SHIFT)



#define ARM_EXIT_WITH_SERROR_BIT  31

#define ARM_EXCEPTION_CODE(x)	  ((x) & ~(1U << ARM_EXIT_WITH_SERROR_BIT))

#define ARM_EXCEPTION_IS_TRAP(x)  (ARM_EXCEPTION_CODE((x)) == ARM_EXCEPTION_TRAP)

arch/arm64/include/asm/kvm_emulate.h

+0 −14
Original line number Diff line number Diff line
@@ -383,20 +383,6 @@ static inline unsigned long kvm_vcpu_get_mpidr_aff(struct kvm_vcpu *vcpu) 
	return vcpu_read_sys_reg(vcpu, MPIDR_EL1) & MPIDR_HWID_BITMASK;

}



static inline bool kvm_arm_get_vcpu_workaround_2_flag(struct kvm_vcpu *vcpu)

{

	return vcpu->arch.workaround_flags & VCPU_WORKAROUND_2_FLAG;

}



static inline void kvm_arm_set_vcpu_workaround_2_flag(struct kvm_vcpu *vcpu,

						      bool flag)

{

	if (flag)

		vcpu->arch.workaround_flags |= VCPU_WORKAROUND_2_FLAG;

	else

		vcpu->arch.workaround_flags &= ~VCPU_WORKAROUND_2_FLAG;

}



static inline void kvm_vcpu_set_be(struct kvm_vcpu *vcpu)

{

	if (vcpu_mode_is_32bit(vcpu)) {

arch/arm64/include/asm/kvm_mmu.h

+0 −17
Original line number Diff line number Diff line
@@ -526,23 +526,6 @@ static inline int kvm_map_vectors(void) 
}

#endif



DECLARE_PER_CPU_READ_MOSTLY(u64, arm64_ssbd_callback_required);



static inline int hyp_map_aux_data(void)

{

	int cpu, err;



	for_each_possible_cpu(cpu) {

		u64 *ptr;



		ptr = per_cpu_ptr(&arm64_ssbd_callback_required, cpu);

		err = create_hyp_mappings(ptr, ptr + 1, PAGE_HYP);

		if (err)

			return err;

	}

	return 0;

}



#define kvm_phys_to_vttbr(addr)		phys_to_ttbr(addr)



/*

arch/arm64/include/uapi/asm/kvm.h

+9 −0
Original line number Diff line number Diff line
@@ -242,6 +242,15 @@ struct kvm_vcpu_events { 
#define KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_AVAIL		0

#define KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_AVAIL		1

#define KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_REQUIRED	2



/*

 * Only two states can be presented by the host kernel:

 * - NOT_REQUIRED: the guest doesn't need to do anything

 * - NOT_AVAIL: the guest isn't mitigated (it can still use SSBS if available)

 *

 * All the other values are deprecated. The host still accepts all

 * values (they are ABI), but will narrow them to the above two.

 */

#define KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2	KVM_REG_ARM_FW_REG(2)

#define KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL		0

#define KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_UNKNOWN		1

arch/arm64/kernel/cpu_errata.c

+0 −14
Original line number Diff line number Diff line
@@ -108,20 +108,6 @@ cpu_enable_trap_ctr_access(const struct arm64_cpu_capabilities *cap) 


int ssbd_state __read_mostly = ARM64_SSBD_UNKNOWN;



void __init arm64_enable_wa2_handling(struct alt_instr *alt,

				      __le32 *origptr, __le32 *updptr,

				      int nr_inst)

{

	BUG_ON(nr_inst != 1);

	/*

	 * Only allow mitigation on EL1 entry/exit and guest

	 * ARCH_WORKAROUND_2 handling if the SSBD state allows it to

	 * be flipped.

	 */

	if (arm64_get_ssbd_state() == ARM64_SSBD_KERNEL)

		*updptr = cpu_to_le32(aarch64_insn_gen_nop());

}



#ifdef CONFIG_ARM64_ERRATUM_1463225

DEFINE_PER_CPU(int, __in_cortex_a76_erratum_1463225_wa);

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