arm64: KVM: Allow the main HYP code to use the init hyp stub implementation

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.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <cdall@linaro.org>

diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S
index d8ef788646c605766d2bfd64b17b98bd790f9803..4f34c5996f86356ba267e9ff48a6221f2458384d 100644 (file)
--- 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:
        /*