Commit c62d7a23 authored by Marc Zyngier's avatar Marc Zyngier Committed by Oliver Upton
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KVM: arm64: Add feature checking helpers 



In order to make it easier to check whether a particular feature
is exposed to a guest, add a new set of helpers, with kvm_has_feat()
being the most useful.

Let's start making use of them in the PMU code (courtesy of Oliver).
Follow-up changes will introduce additional use patterns.

Reviewed-by: default avatarSuzuki K Poulose <suzuki.poulose@arm.com>
Co-developed--by: default avatarOliver Upton <oliver.upton@linux.dev>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240214131827.2856277-3-maz@kernel.org


Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
parent aeddd5b2

arch/arm64/include/asm/kvm_host.h

+44 −0
Original line number Diff line number Diff line
@@ -1233,4 +1233,48 @@ static inline void kvm_hyp_reserve(void) { } 
void kvm_arm_vcpu_power_off(struct kvm_vcpu *vcpu);

bool kvm_arm_vcpu_stopped(struct kvm_vcpu *vcpu);



#define __expand_field_sign_unsigned(id, fld, val)			\

	((u64)SYS_FIELD_VALUE(id, fld, val))



#define __expand_field_sign_signed(id, fld, val)			\

	({								\

		u64 __val = SYS_FIELD_VALUE(id, fld, val);		\

		sign_extend64(__val, id##_##fld##_WIDTH - 1);		\

	})



#define expand_field_sign(id, fld, val)					\

	(id##_##fld##_SIGNED ?						\

	 __expand_field_sign_signed(id, fld, val) :			\

	 __expand_field_sign_unsigned(id, fld, val))



#define get_idreg_field_unsigned(kvm, id, fld)				\

	({								\

		u64 __val = IDREG((kvm), SYS_##id);			\

		FIELD_GET(id##_##fld##_MASK, __val);			\

	})



#define get_idreg_field_signed(kvm, id, fld)				\

	({								\

		u64 __val = get_idreg_field_unsigned(kvm, id, fld);	\

		sign_extend64(__val, id##_##fld##_WIDTH - 1);		\

	})



#define get_idreg_field_enum(kvm, id, fld)				\

	get_idreg_field_unsigned(kvm, id, fld)



#define get_idreg_field(kvm, id, fld)					\

	(id##_##fld##_SIGNED ?						\

	 get_idreg_field_signed(kvm, id, fld) :				\

	 get_idreg_field_unsigned(kvm, id, fld))



#define kvm_has_feat(kvm, id, fld, limit)				\

	(get_idreg_field((kvm), id, fld) >= expand_field_sign(id, fld, limit))



#define kvm_has_feat_enum(kvm, id, fld, val)				\

	(get_idreg_field_unsigned((kvm), id, fld) == __expand_field_sign_unsigned(id, fld, val))



#define kvm_has_feat_range(kvm, id, fld, min, max)			\

	(get_idreg_field((kvm), id, fld) >= expand_field_sign(id, fld, min) && \

	 get_idreg_field((kvm), id, fld) <= expand_field_sign(id, fld, max))



#endif /* __ARM64_KVM_HOST_H__ */

arch/arm64/kvm/pmu-emul.c

+6 −5
Original line number Diff line number Diff line
@@ -64,12 +64,11 @@ u64 kvm_pmu_evtyper_mask(struct kvm *kvm) 
{

	u64 mask = ARMV8_PMU_EXCLUDE_EL1 | ARMV8_PMU_EXCLUDE_EL0 |

		   kvm_pmu_event_mask(kvm);

	u64 pfr0 = IDREG(kvm, SYS_ID_AA64PFR0_EL1);



	if (SYS_FIELD_GET(ID_AA64PFR0_EL1, EL2, pfr0))

	if (kvm_has_feat(kvm, ID_AA64PFR0_EL1, EL2, IMP))

		mask |= ARMV8_PMU_INCLUDE_EL2;



	if (SYS_FIELD_GET(ID_AA64PFR0_EL1, EL3, pfr0))

	if (kvm_has_feat(kvm, ID_AA64PFR0_EL1, EL3, IMP))

		mask |= ARMV8_PMU_EXCLUDE_NS_EL0 |

			ARMV8_PMU_EXCLUDE_NS_EL1 |

			ARMV8_PMU_EXCLUDE_EL3;
@@ -83,8 +82,10 @@ u64 kvm_pmu_evtyper_mask(struct kvm *kvm) 
 */

static bool kvm_pmc_is_64bit(struct kvm_pmc *pmc)

{

	struct kvm_vcpu *vcpu = kvm_pmc_to_vcpu(pmc);



	return (pmc->idx == ARMV8_PMU_CYCLE_IDX ||

		kvm_pmu_is_3p5(kvm_pmc_to_vcpu(pmc)));

		kvm_has_feat(vcpu->kvm, ID_AA64DFR0_EL1, PMUVer, V3P5));

}



static bool kvm_pmc_has_64bit_overflow(struct kvm_pmc *pmc)
@@ -556,7 +557,7 @@ void kvm_pmu_handle_pmcr(struct kvm_vcpu *vcpu, u64 val) 
		return;



	/* Fixup PMCR_EL0 to reconcile the PMU version and the LP bit */

	if (!kvm_pmu_is_3p5(vcpu))

	if (!kvm_has_feat(vcpu->kvm, ID_AA64DFR0_EL1, PMUVer, V3P5))

		val &= ~ARMV8_PMU_PMCR_LP;



	/* The reset bits don't indicate any state, and shouldn't be saved. */

arch/arm64/kvm/sys_regs.c

+2 −4
Original line number Diff line number Diff line
@@ -505,10 +505,9 @@ static bool trap_loregion(struct kvm_vcpu *vcpu, 
			  struct sys_reg_params *p,

			  const struct sys_reg_desc *r)

{

	u64 val = IDREG(vcpu->kvm, SYS_ID_AA64MMFR1_EL1);

	u32 sr = reg_to_encoding(r);



	if (!(val & (0xfUL << ID_AA64MMFR1_EL1_LO_SHIFT))) {

	if (!kvm_has_feat(vcpu->kvm, ID_AA64MMFR1_EL1, LO, IMP)) {

		kvm_inject_undefined(vcpu);

		return false;

	}
@@ -2748,8 +2747,7 @@ static bool trap_dbgdidr(struct kvm_vcpu *vcpu, 
		return ignore_write(vcpu, p);

	} else {

		u64 dfr = IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1);

		u64 pfr = IDREG(vcpu->kvm, SYS_ID_AA64PFR0_EL1);

		u32 el3 = !!SYS_FIELD_GET(ID_AA64PFR0_EL1, EL3, pfr);

		u32 el3 = kvm_has_feat(vcpu->kvm, ID_AA64PFR0_EL1, EL3, IMP);



		p->regval = ((SYS_FIELD_GET(ID_AA64DFR0_EL1, WRPs, dfr) << 28) |

			     (SYS_FIELD_GET(ID_AA64DFR0_EL1, BRPs, dfr) << 24) |

include/kvm/arm_pmu.h

+0 −11
Original line number Diff line number Diff line
@@ -90,16 +90,6 @@ void kvm_vcpu_pmu_resync_el0(void); 
			vcpu->arch.pmu.events = *kvm_get_pmu_events();	\

	} while (0)



/*

 * Evaluates as true when emulating PMUv3p5, and false otherwise.

 */

#define kvm_pmu_is_3p5(vcpu) ({						\

	u64 val = IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1);		\

	u8 pmuver = SYS_FIELD_GET(ID_AA64DFR0_EL1, PMUVer, val);	\

									\

	pmuver >= ID_AA64DFR0_EL1_PMUVer_V3P5;				\

})



u8 kvm_arm_pmu_get_pmuver_limit(void);

u64 kvm_pmu_evtyper_mask(struct kvm *kvm);

int kvm_arm_set_default_pmu(struct kvm *kvm);
@@ -168,7 +158,6 @@ static inline u64 kvm_pmu_get_pmceid(struct kvm_vcpu *vcpu, bool pmceid1) 
}



#define kvm_vcpu_has_pmu(vcpu)		({ false; })

#define kvm_pmu_is_3p5(vcpu)		({ false; })

static inline void kvm_pmu_update_vcpu_events(struct kvm_vcpu *vcpu) {}

static inline void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu) {}

static inline void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu) {}