Hi,
On 2/21/19 5:20 PM, Mark Rutland wrote:
Hi,
On Tue, Feb 19, 2019 at 02:54:26PM +0530, Amit Daniel Kachhap wrote:
From: Mark Rutland <mark.rutland@xxxxxxx>
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@xxxxxxx>
[Added __cpu_copy_hyp_conf, hcr_el2 field in struct kvm_cpu_context]
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@xxxxxxx>
Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
Cc: Christoffer Dall <christoffer.dall@xxxxxxx>
Cc: kvmarm@xxxxxxxxxxxxxxxxxxxxx
[...]
+/**
+ * __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.
ok, Agreed with the name.
[...]
+/**
+ * __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?
Yes it works fine for VHE. I missed this.
Thanks,
Amit
Thanks,
Mark.
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