Commit ad72e59f authored by Geoff Levand's avatar Geoff Levand Committed by Will Deacon
Browse files

arm64: hyp/kvm: Make hyp-stub extensible 



The existing arm64 hcall implementations are limited in that they only
allow for two distinct hcalls; with the x0 register either zero or not
zero.  Also, the API of the hyp-stub exception vector routines and the
KVM exception vector routines differ; hyp-stub uses a non-zero value in
x0 to implement __hyp_set_vectors, whereas KVM uses it to implement
kvm_call_hyp.

To allow for additional hcalls to be defined and to make the arm64 hcall
API more consistent across exception vector routines, change the hcall
implementations to reserve all x0 values below 0xfff for hcalls such
as {s,g}et_vectors().

Define two new preprocessor macros HVC_GET_VECTORS, and HVC_SET_VECTORS
to be used as hcall type specifiers and convert the existing
__hyp_get_vectors() and __hyp_set_vectors() routines to use these new
macros when executing an HVC call.  Also, change the corresponding
hyp-stub and KVM el1_sync exception vector routines to use these new
macros.

Signed-off-by: default avatarGeoff Levand <geoff@infradead.org>
[Merged two hcall patches, moved immediate value from esr to x0, use lr
 as a scratch register, changed limit to 0xfff]
Signed-off-by: default avatarJames Morse <james.morse@arm.com>
Acked-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 00a44cda

arch/arm64/include/asm/virt.h

+16 −0
Original line number Diff line number Diff line
@@ -18,6 +18,22 @@ 
#ifndef __ASM__VIRT_H

#define __ASM__VIRT_H



/*

 * The arm64 hcall implementation uses x0 to specify the hcall type. A value

 * less than 0xfff indicates a special hcall, such as get/set vector.

 * Any other value is used as a pointer to the function to call.

 */



/* HVC_GET_VECTORS - Return the value of the vbar_el2 register. */

#define HVC_GET_VECTORS 0



/*

 * HVC_SET_VECTORS - Set the value of the vbar_el2 register.

 *

 * @x1: Physical address of the new vector table.

 */

#define HVC_SET_VECTORS 1



#define BOOT_CPU_MODE_EL1	(0xe11)

#define BOOT_CPU_MODE_EL2	(0xe12)

arch/arm64/kernel/hyp-stub.S

+24 −10
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
#include <linux/irqchip/arm-gic-v3.h>



#include <asm/assembler.h>

#include <asm/kvm_arm.h>

#include <asm/ptrace.h>

#include <asm/virt.h>
@@ -53,15 +54,26 @@ ENDPROC(__hyp_stub_vectors) 
	.align 11



el1_sync:

	mrs	x1, esr_el2

	lsr	x1, x1, #26

	cmp	x1, #0x16

	b.ne	2f				// Not an HVC trap

	cbz	x0, 1f

	msr	vbar_el2, x0			// Set vbar_el2

	b	2f

1:	mrs	x0, vbar_el2			// Return vbar_el2

2:	eret

	mrs	x30, esr_el2

	lsr	x30, x30, #ESR_ELx_EC_SHIFT



	cmp	x30, #ESR_ELx_EC_HVC64

	b.ne	9f				// Not an HVC trap



	cmp	x0, #HVC_GET_VECTORS

	b.ne	1f

	mrs	x0, vbar_el2

	b	9f



1:	cmp	x0, #HVC_SET_VECTORS

	b.ne	2f

	msr	vbar_el2, x1

	b	9f



	/* Unrecognised call type */

2:	mov     x0, xzr



9:	eret

ENDPROC(el1_sync)



.macro invalid_vector	label
@@ -102,7 +114,7 @@ ENDPROC(\label) 


ENTRY(__hyp_get_vectors)

	str	lr, [sp, #-16]!

	mov	x0, xzr

	mov	x0, #HVC_GET_VECTORS

	hvc	#0

	ldr	lr, [sp], #16

	ret
@@ -110,6 +122,8 @@ ENDPROC(__hyp_get_vectors) 


ENTRY(__hyp_set_vectors)

	str	lr, [sp, #-16]!

	mov	x1, x0

	mov	x0, #HVC_SET_VECTORS

	hvc	#0

	ldr	lr, [sp], #16

	ret

arch/arm64/kvm/hyp.S

+2 −2
Original line number Diff line number Diff line
@@ -35,8 +35,8 @@ 
 * in Hyp mode (see init_hyp_mode in arch/arm/kvm/arm.c).  Return values are

 * passed in x0.

 *

 * A function pointer with a value of 0 has a special meaning, and is

 * used to implement __hyp_get_vectors in the same way as in

 * A function pointer with a value less than 0xfff has a special meaning,

 * and is used to implement __hyp_get_vectors in the same way as in

 * arch/arm64/kernel/hyp_stub.S.

 * HVC behaves as a 'bl' call and will clobber lr.

 */

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

+2 −2
Original line number Diff line number Diff line
@@ -82,8 +82,8 @@ alternative_endif 
	/* Here, we're pretty sure the host called HVC. */

	restore_x0_to_x3



	/* Check for __hyp_get_vectors */

	cbnz	x0, 1f

	cmp	x0, #HVC_GET_VECTORS

	b.ne	1f

	mrs	x0, vbar_el2

	b	2f

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