arm: KVM: Simplify HYP init

Just like for arm64, we can now make the HYP setup a lot simpler,
and we can now initialise it in one go (instead of the two
phases we currently have).

Signed-off-by: Marc Zyngier <[e-mail]>
Signed-off-by: Christoffer Dall <[e-mail]>

arch/arm/include/asm/kvm_host.h

···
 	 * code. The init code doesn't need to preserve these
 	 * registers as r0-r3 are already callee saved according to
 	 * the AAPCS.
-	 * Note that we slightly misuse the prototype by casing the
+	 * Note that we slightly misuse the prototype by casting the
 	 * stack pointer to a void *.
-	 *
-	 * We don't have enough registers to perform the full init in
-	 * one go.  Install the boot PGD first, and then install the
-	 * runtime PGD, stack pointer and vectors. The PGDs are always
-	 * passed as the third argument, in order to be passed into
-	 * r2-r3 to the init code (yes, this is compliant with the
-	 * PCS!).
-	 */
 
-	kvm_call_hyp(NULL, 0, boot_pgd_ptr);
+	 * The PGDs are always passed as the third argument, in order
+	 * to be passed into r2-r3 to the init code (yes, this is
+	 * compliant with the PCS!).
+	 */
 
 	kvm_call_hyp((void*)hyp_stack_ptr, vector_ptr, pgd_ptr);
 }

arch/arm/kvm/init.S

···
  *       r2,r3 = Hypervisor pgd pointer
  *
  * The init scenario is:
- * - We jump in HYP with four parameters: boot HYP pgd, runtime HYP pgd,
- *   runtime stack, runtime vectors
- * - Enable the MMU with the boot pgd
- * - Jump to a target into the trampoline page (remember, this is the same
- *   physical page!)
- * - Now switch to the runtime pgd (same VA, and still the same physical
- *   page!)
+ * - We jump in HYP with 3 parameters: runtime HYP pgd, runtime stack,
+ *   runtime vectors
  * - Invalidate TLBs
  * - Set stack and vectors
+ * - Setup the page tables
+ * - Enable the MMU
  * - Profit! (or eret, if you only care about the code).
- *
- * As we only have four registers available to pass parameters (and we
- * need six), we split the init in two phases:
- * - Phase 1: r0 = 0, r1 = 0, r2,r3 contain the boot PGD.
- *   Provides the basic HYP init, and enable the MMU.
- * - Phase 2: r0 = ToS, r1 = vectors, r2,r3 contain the runtime PGD.
- *   Switches to the runtime PGD, set stack and vectors.
  */
 
 	.text
···
 	W(b)	.
 
 __do_hyp_init:
-	cmp	r0, #0			@ We have a SP?
-	bne	phase2			@ Yes, second stage init
+	@ Set stack pointer
+	mov	sp, r0
+
+	@ Set HVBAR to point to the HYP vectors
+	mcr	p15, 4, r1, c12, c0, 0	@ HVBAR
 
 	@ Set the HTTBR to point to the hypervisor PGD pointer passed
 	mcrr	p15, 4, rr_lo_hi(r2, r3), c2
···
  THUMB(	ldr	r2, =(HSCTLR_M | HSCTLR_A | HSCTLR_TE)		)
 	orr	r1, r1, r2
 	orr	r0, r0, r1
-	isb
 	mcr	p15, 4, r0, c1, c0, 0	@ HSCR
-
-	@ End of init phase-1
-	eret
-
-phase2:
-	@ Set stack pointer
-	mov	sp, r0
-
-	@ Set HVBAR to point to the HYP vectors
-	mcr	p15, 4, r1, c12, c0, 0	@ HVBAR
-
-	@ Jump to the trampoline page
-	ldr	r0, =TRAMPOLINE_VA
-	adr	r1, target
-	bfi	r0, r1, #0, #PAGE_SHIFT
-	ret	r0
-
-target:	@ We're now in the trampoline code, switch page tables
-	mcrr	p15, 4, rr_lo_hi(r2, r3), c2
 	isb
-
-	@ Invalidate the old TLBs
-	mcr	p15, 4, r0, c8, c7, 0	@ TLBIALLH
-	dsb	ish
 
 	eret