[PATCH v4 07/28] arm64: KVM: Allow the main HYP code to use the init hyp stub implementation

Marc Zyngier
2017-03-21T19:20:37Z

We now have a full hyp-stub implementation in the KVM init code,
but the main KVM code only supports HVC_GET_VECTORS, which is not
enough.

Instead of reinventing the wheel, let's reuse the init implementation
by branching to the idmap page when called with a hyp-stub hypercall.

Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
arch/arm64/kvm/hyp/hyp-entry.S | 24 +++++++++++++++++++-----
1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S
index d8ef788646c6..4f34c5996f86 100644
--- a/arch/arm64/kvm/hyp/hyp-entry.S
+++ b/arch/arm64/kvm/hyp/hyp-entry.S
@@ -87,10 +87,24 @@ alternative_endif
/* Here, we're pretty sure the host called HVC. */
ldp x0, x1, [sp], #16

- cmp x0, #HVC_GET_VECTORS
- b.ne 1f
- mrs x0, vbar_el2
- b 2f
+ /* Check for a stub HVC call */
+ cmp x0, #HVC_STUB_HCALL_NR
+ b.hs 1f
+
+ /*
+ * Compute the idmap address of __kvm_handle_stub_hvc and
+ * jump there. Since we use kimage_voffset, do not use the
+ * HYP VA for __kvm_handle_stub_hvc, but the kernel VA instead
+ * (by loading it from the constant pool).
+ *
+ * Preserve x0-x4, which may contain stub parameters.
+ */
+ ldr x5, =__kvm_handle_stub_hvc
+ ldr_l x6, kimage_voffset
+
+ /* x5 = __pa(x5) */
+ sub x5, x5, x6
+ br x5

1:
/*
@@ -99,7 +113,7 @@ alternative_endif
kern_hyp_va x0
do_el2_call

-2: eret
+ eret

el1_trap:
/*
--
2.11.0