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KVM: arm64: Add some more comments in kvm_hyp_handle_fpsimd()

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The handling for FPSIMD/SVE traps is multi stage and involves some trap
manipulation which isn't quite so immediately obvious as might be desired
so add a few more comments.

Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220124155720.3943374-3-broonie@kernel.org
This commit is contained in:
Mark Brown 2022-01-24 15:57:20 +00:00 committed by Marc Zyngier
parent 23afc82539
commit 01a244decc
1 changed files with 4 additions and 0 deletions
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4
arch/arm64/kvm/hyp/include/hyp/switch.h
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@ -173,6 +173,8 @@ static bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code)
return false;
/* Valid trap. Switch the context: */
/* First disable enough traps to allow us to update the registers */
if (has_vhe()) {
reg = CPACR_EL1_FPEN;
if (sve_guest)
@ -188,11 +190,13 @@ static bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code)
}
isb();
/* Write out the host state if it's in the registers */
if (vcpu->arch.flags & KVM_ARM64_FP_HOST) {
__fpsimd_save_state(vcpu->arch.host_fpsimd_state);
vcpu->arch.flags &= ~KVM_ARM64_FP_HOST;
}
/* Restore the guest state */
if (sve_guest)
__hyp_sve_restore_guest(vcpu);
else