niansa-misc/linux
1
0
Fork 0
mirror of synced 2025-03-06 20:59:54 +01:00
Code Issues Projects Releases Packages Wiki Activity

KVM: arm64: nv: Ensure correct VL is loaded before saving SVE state

Browse source 
It is possible that the guest hypervisor has selected a smaller VL than
the maximum for its nested guest. As such, ZCR_EL2 may be configured for
a different VL when exiting a nested guest.

Set ZCR_EL2 (via the EL1 alias) to the maximum VL for the VM before
saving SVE state as the SVE save area is dimensioned by the max VL.

Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240620164653.1130714-8-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
This commit is contained in:
Oliver Upton 2024-06-20 16:46:44 +00:00
parent 9092aca9fe
commit 2e3cf82063
1 changed files with 7 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

11
arch/arm64/kvm/fpsimd.c
View file

@ -195,11 +195,14 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
* Note that this means that at guest exit ZCR_EL1 is
* not necessarily the same as on guest entry.
*
* Restoring the VL isn't needed in VHE mode since
* ZCR_EL2 (accessed via ZCR_EL1) would fulfill the same
* role when doing the save from EL2.
* ZCR_EL2 holds the guest hypervisor's VL when running
* a nested guest, which could be smaller than the
* max for the vCPU. Similar to above, we first need to
* switch to a VL consistent with the layout of the
* vCPU's SVE state. KVM support for NV implies VHE, so
* using the ZCR_EL1 alias is safe.
*/
if (!has_vhe())
if (!has_vhe() || (vcpu_has_nv(vcpu) && !is_hyp_ctxt(vcpu)))
sve_cond_update_zcr_vq(vcpu_sve_max_vq(vcpu) - 1,
SYS_ZCR_EL1);
}