Messages in this thread | | | Date | Thu, 21 Feb 2019 11:50:34 +0000 | From | Mark Rutland <> | Subject | Re: [PATCH v6 1/6] arm64/kvm: preserve host HCR_EL2 value |
| |
Hi,
On Tue, Feb 19, 2019 at 02:54:26PM +0530, Amit Daniel Kachhap wrote: > From: Mark Rutland <mark.rutland@arm.com> > > When restoring HCR_EL2 for the host, KVM uses HCR_HOST_VHE_FLAGS, which > is a constant value. This works today, as the host HCR_EL2 value is > always the same, but this will get in the way of supporting extensions > that require HCR_EL2 bits to be set conditionally for the host. > > To allow such features to work without KVM having to explicitly handle > every possible host feature combination, this patch has KVM save/restore > for the host HCR when switching to/from a guest HCR. The saving of the > register is done once during cpu hypervisor initialization state and is > just restored after switch from guest. > > For fetching HCR_EL2 during kvm initialisation, a hyp call is made using > kvm_call_hyp and is helpful in NHVE case. > > For the hyp TLB maintenance code, __tlb_switch_to_host_vhe() is updated > to toggle the TGE bit with a RMW sequence, as we already do in > __tlb_switch_to_guest_vhe(). > > The value of hcr_el2 is now stored in struct kvm_cpu_context as both host > and guest can now use this field in a common way. > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> > [Added __cpu_copy_hyp_conf, hcr_el2 field in struct kvm_cpu_context] > Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com> > Cc: Marc Zyngier <marc.zyngier@arm.com> > Cc: Christoffer Dall <christoffer.dall@arm.com> > Cc: kvmarm@lists.cs.columbia.edu
[...]
> +/** > + * __cpu_copy_hyp_conf - copy the boot hyp configuration registers > + * > + * It is called once per-cpu during CPU hyp initialisation. > + */ > +static inline void __cpu_copy_hyp_conf(void)
I think this would be better named as something like:
cpu_init_host_ctxt()
... as that makes it a bit clearer as to what is being initialized.
[...]
> +/** > + * __kvm_populate_host_regs - Stores host register values > + * > + * This function acts as a function handler parameter for kvm_call_hyp and > + * may be called from EL1 exception level to fetch the register value. > + */ > +void __hyp_text __kvm_populate_host_regs(void) > +{ > + struct kvm_cpu_context *host_ctxt; > + > + if (has_vhe()) > + host_ctxt = this_cpu_ptr(&kvm_host_cpu_state); > + else > + host_ctxt = __hyp_this_cpu_ptr(kvm_host_cpu_state);
Do we need the has_vhe() check here?
Can't we always do:
host_ctxt = __hyp_this_cpu_ptr(kvm_host_cpu_state);
... regardless of VHE? Or is that broken for VHE somehow?
Thanks, Mark.
| |