Commit b81125c7 authored by Marc Zyngier's avatar Marc Zyngier
Browse files

arm64: KVM: VHE: Patch out use of HVC 



With VHE, the host never issues an HVC instruction to get into the
KVM code, as we can simply branch there.

Use runtime code patching to simplify things a bit.

Reviewed-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
parent 1e947bad

arch/arm64/kvm/hyp.S

+7 −0
Original line number Diff line number Diff line
@@ -17,7 +17,9 @@ 


#include <linux/linkage.h>



#include <asm/alternative.h>

#include <asm/assembler.h>

#include <asm/cpufeature.h>



/*

 * u64 kvm_call_hyp(void *hypfn, ...);
@@ -38,6 +40,11 @@ 
 * arch/arm64/kernel/hyp_stub.S.

 */

ENTRY(kvm_call_hyp)

alternative_if_not ARM64_HAS_VIRT_HOST_EXTN	

	hvc	#0

	ret

alternative_else

	b	__vhe_hyp_call

	nop

alternative_endif

ENDPROC(kvm_call_hyp)

arch/arm64/kvm/hyp/hyp-entry.S

+31 −9
Original line number Diff line number Diff line
@@ -38,6 +38,34 @@ 
	ldp	x0, x1, [sp], #16

.endm



.macro do_el2_call

	/*

	 * Shuffle the parameters before calling the function

	 * pointed to in x0. Assumes parameters in x[1,2,3].

	 */

	sub	sp, sp, #16

	str	lr, [sp]

	mov	lr, x0

	mov	x0, x1

	mov	x1, x2

	mov	x2, x3

	blr	lr

	ldr	lr, [sp]

	add	sp, sp, #16

.endm



ENTRY(__vhe_hyp_call)

	do_el2_call

	/*

	 * We used to rely on having an exception return to get

	 * an implicit isb. In the E2H case, we don't have it anymore.

	 * rather than changing all the leaf functions, just do it here

	 * before returning to the rest of the kernel.

	 */

	isb

	ret

ENDPROC(__vhe_hyp_call)

	

el1_sync:				// Guest trapped into EL2

	save_x0_to_x3
@@ -58,19 +86,13 @@ el1_sync: // Guest trapped into EL2 
	mrs	x0, vbar_el2

	b	2f



1:	stp	lr, xzr, [sp, #-16]!



1:

	/*

	 * Compute the function address in EL2, and shuffle the parameters.

	 * Perform the EL2 call

	 */

	kern_hyp_va	x0

	mov	lr, x0

	mov	x0, x1

	mov	x1, x2

	mov	x2, x3

	blr	lr

	do_el2_call



	ldp	lr, xzr, [sp], #16

2:	eret



el1_trap: