Hi Christoffer,
On 08/02/18 18:04, Christoffer Dall wrote:
On Tue, Jan 09, 2018 at 07:04:08PM +0000, Suzuki K Poulose wrote:
We set VTCR_EL2 very early during the stage2 init and don't
touch it ever. This is fine as we had a fixed IPA size. This
patch changes the behavior to set the VTCR for a given VM,
depending on its stage2 table. The common configuration for
VTCR is still performed during the early init. But the SL0
and T0SZ are programmed for each VM and is cleared once we
exit the VM.
Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
Cc: Christoffer Dall <cdall@xxxxxxxxxx>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
index f7c651f3a8c0..523471f0af7b 100644
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -157,11 +157,20 @@ static void __hyp_text __deactivate_traps(struct kvm_vcpu *vcpu)
static void __hyp_text __activate_vm(struct kvm_vcpu *vcpu)
{
struct kvm *kvm = kern_hyp_va(vcpu->kvm);
+ u64 vtcr = read_sysreg(vtcr_el2);
+
+ vtcr &= ~VTCR_EL2_PRIVATE_MASK;
+ vtcr |= VTCR_EL2_SL0(stage2_pt_levels(kvm)) |
+ VTCR_EL2_T0SZ(kvm_phys_shift(kvm));
+ write_sysreg(vtcr, vtcr_el2);
If we're writing VTCR_EL2 on each entry, do we really need to read the
value back first and calculate things on every entry to the VM? It
seems to me we should be able to compute the vtcr_el2 and store it on
struct kvm, and simply restore that per-VM value upon entering the VM?
I took a look at this and we need to do this to make sure we retain the
Hardware update of Access flags for stage2 (VTCR_EL2_HA) bits on the CPUs
that has it and it is safe to run a mix of CPUs with and without the feature.
write_sysreg(kvm->arch.vttbr, vttbr_el2);
}
static void __hyp_text __deactivate_vm(struct kvm_vcpu *vcpu)
{
+ u64 vtcr = read_sysreg(vtcr_el2) & ~VTCR_EL2_PRIVATE_MASK;
+
+ write_sysreg(vtcr, vtcr_el2);
Why do we need to care about restoring VTCR when returning to the host?
Yes, this can be skipped.
Cheers
Suzuki
