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KVM: arm64: Refactor CPTR trap deactivation

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For historical reasons, the VHE and nVHE/hVHE implementations of
__activate_cptr_traps() pair with a common implementation of
__kvm_reset_cptr_el2(), which ideally would be named
__deactivate_cptr_traps().

Rename __kvm_reset_cptr_el2() to __deactivate_cptr_traps(), and split it
into separate VHE and nVHE/hVHE variants so that each can be paired with
its corresponding implementation of __activate_cptr_traps().

At the same time, fold kvm_write_cptr_el2() into its callers. This
makes it clear in-context whether a write is made to the CPACR_EL1
encoding or the CPTR_EL2 encoding, and removes the possibility of
confusion as to whether kvm_write_cptr_el2() reformats the sysreg fields
as cpacr_clear_set() does.

In the nVHE/hVHE implementation of __activate_cptr_traps(), placing the
sysreg writes within the if-else blocks requires that the call to
__activate_traps_fpsimd32() is moved earlier, but as this was always
called before writing to CPTR_EL2/CPACR_EL1, this should not result in a
functional change.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Fuad Tabba <tabba@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20250210195226.1215254-6-mark.rutland@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Mark Rutland 2025-02-10 19:52:23 +00:00 • committed by Marc Zyngier
parent 407a99c465
commit ee14db31a9
3 changed files with 42 additions and 47 deletions
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42
arch/arm64/include/asm/kvm_emulate.h
View file

@ -605,48 +605,6 @@ static __always_inline void kvm_incr_pc(struct kvm_vcpu *vcpu)
__cpacr_to_cptr_set(clr, set));\
} while (0)
static __always_inline void kvm_write_cptr_el2(u64 val)
{
if (has_vhe() || has_hvhe())
write_sysreg(val, cpacr_el1);
else
write_sysreg(val, cptr_el2);
}
/* Resets the value of cptr_el2 when returning to the host. */
static __always_inline void __kvm_reset_cptr_el2(struct kvm *kvm)
{
u64 val;
if (has_vhe()) {
val = (CPACR_EL1_FPEN | CPACR_EL1_ZEN_EL1EN);
if (cpus_have_final_cap(ARM64_SME))
val |= CPACR_EL1_SMEN_EL1EN;
} else if (has_hvhe()) {
val = CPACR_EL1_FPEN;
if (!kvm_has_sve(kvm) || !guest_owns_fp_regs())
val |= CPACR_EL1_ZEN;
if (cpus_have_final_cap(ARM64_SME))
val |= CPACR_EL1_SMEN;
} else {
val = CPTR_NVHE_EL2_RES1;
if (kvm_has_sve(kvm) && guest_owns_fp_regs())
val |= CPTR_EL2_TZ;
if (!cpus_have_final_cap(ARM64_SME))
val |= CPTR_EL2_TSM;
}
kvm_write_cptr_el2(val);
}
#ifdef __KVM_NVHE_HYPERVISOR__
#define kvm_reset_cptr_el2(v) __kvm_reset_cptr_el2(kern_hyp_va((v)->kvm))
#else
#define kvm_reset_cptr_el2(v) __kvm_reset_cptr_el2((v)->kvm)
#endif
/*
* Returns a 'sanitised' view of CPTR_EL2, translating from nVHE to the VHE
* format if E2H isn't set.

35
arch/arm64/kvm/hyp/nvhe/switch.c
View file

@ -39,6 +39,9 @@ static void __activate_cptr_traps(struct kvm_vcpu *vcpu)
{
u64 val = CPTR_EL2_TAM; /* Same bit irrespective of E2H */
if (!guest_owns_fp_regs())
__activate_traps_fpsimd32(vcpu);
if (has_hvhe()) {
val |= CPACR_EL1_TTA;
@ -47,6 +50,8 @@ static void __activate_cptr_traps(struct kvm_vcpu *vcpu)
if (vcpu_has_sve(vcpu))
val |= CPACR_EL1_ZEN;
}
write_sysreg(val, cpacr_el1);
} else {
val |= CPTR_EL2_TTA | CPTR_NVHE_EL2_RES1;
@ -61,12 +66,34 @@ static void __activate_cptr_traps(struct kvm_vcpu *vcpu)
if (!guest_owns_fp_regs())
val |= CPTR_EL2_TFP;
write_sysreg(val, cptr_el2);
}
}
if (!guest_owns_fp_regs())
__activate_traps_fpsimd32(vcpu);
static void __deactivate_cptr_traps(struct kvm_vcpu *vcpu)
{
struct kvm *kvm = kern_hyp_va(vcpu->kvm);
kvm_write_cptr_el2(val);
if (has_hvhe()) {
u64 val = CPACR_EL1_FPEN;
if (!kvm_has_sve(kvm) || !guest_owns_fp_regs())
val |= CPACR_EL1_ZEN;
if (cpus_have_final_cap(ARM64_SME))
val |= CPACR_EL1_SMEN;
write_sysreg(val, cpacr_el1);
} else {
u64 val = CPTR_NVHE_EL2_RES1;
if (kvm_has_sve(kvm) && guest_owns_fp_regs())
val |= CPTR_EL2_TZ;
if (!cpus_have_final_cap(ARM64_SME))
val |= CPTR_EL2_TSM;
write_sysreg(val, cptr_el2);
}
}
static void __activate_traps(struct kvm_vcpu *vcpu)
@ -119,7 +146,7 @@ static void __deactivate_traps(struct kvm_vcpu *vcpu)
write_sysreg(this_cpu_ptr(&kvm_init_params)->hcr_el2, hcr_el2);
kvm_reset_cptr_el2(vcpu);
__deactivate_cptr_traps(vcpu);
write_sysreg(__kvm_hyp_host_vector, vbar_el2);
}

12
arch/arm64/kvm/hyp/vhe/switch.c
View file

@ -136,6 +136,16 @@ write:
write_sysreg(val, cpacr_el1);
}
static void __deactivate_cptr_traps(struct kvm_vcpu *vcpu)
{
u64 val = CPACR_EL1_FPEN | CPACR_EL1_ZEN_EL1EN;
if (cpus_have_final_cap(ARM64_SME))
val |= CPACR_EL1_SMEN_EL1EN;
write_sysreg(val, cpacr_el1);
}
static void __activate_traps(struct kvm_vcpu *vcpu)
{
u64 val;
@ -207,7 +217,7 @@ static void __deactivate_traps(struct kvm_vcpu *vcpu)
*/
asm(ALTERNATIVE("nop", "isb", ARM64_WORKAROUND_SPECULATIVE_AT));
kvm_reset_cptr_el2(vcpu);
__deactivate_cptr_traps(vcpu);
if (!arm64_kernel_unmapped_at_el0())
host_vectors = __this_cpu_read(this_cpu_vector);