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KVM: arm64: nv: Use guest hypervisor's max VL when running nested guest

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The max VL for nested guests is additionally constrained by the max VL
selected by the guest hypervisor. Use that instead of KVM's max VL when
running a nested guest.

Note that the guest hypervisor's ZCR_EL2 is sanitised against the VM's
max VL at the time of access, so there's no additional handling required
at the time of use.

Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240620164653.1130714-7-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
This commit is contained in:
Oliver Upton 2024-06-20 16:46:43 +00:00
parent b7e5c94264
commit 9092aca9fe
1 changed files with 12 additions and 0 deletions
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12
arch/arm64/kvm/hyp/include/hyp/switch.h
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@ -314,11 +314,23 @@ static bool kvm_hyp_handle_mops(struct kvm_vcpu *vcpu, u64 *exit_code)
static inline void __hyp_sve_restore_guest(struct kvm_vcpu *vcpu)
{
/*
* The vCPU's saved SVE state layout always matches the max VL of the
* vCPU. Start off with the max VL so we can load the SVE state.
*/
sve_cond_update_zcr_vq(vcpu_sve_max_vq(vcpu) - 1, SYS_ZCR_EL2);
__sve_restore_state(vcpu_sve_pffr(vcpu),
&vcpu->arch.ctxt.fp_regs.fpsr,
true);
/*
* The effective VL for a VM could differ from the max VL when running a
* nested guest, as the guest hypervisor could select a smaller VL. Slap
* that into hardware before wrapping up.
*/
if (vcpu_has_nv(vcpu) && !is_hyp_ctxt(vcpu))
sve_cond_update_zcr_vq(__vcpu_sys_reg(vcpu, ZCR_EL2), SYS_ZCR_EL2);
write_sysreg_el1(__vcpu_sys_reg(vcpu, vcpu_sve_zcr_elx(vcpu)), SYS_ZCR);
}