Commit 68b824e4 authored by Marc Zyngier's avatar Marc Zyngier
Browse files

KVM: arm64: Patch kimage_voffset instead of loading the EL1 value 



Directly using the kimage_voffset variable is fine for now, but
will become more problematic as we start distrusting EL1.

Instead, patch the kimage_voffset into the HYP text, ensuring
we don't have to load an untrusted value later on.

Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent 7cd0aaaf

arch/arm64/include/asm/kvm_mmu.h

+22 −0
Original line number Diff line number Diff line
@@ -72,6 +72,28 @@ alternative_cb kvm_update_va_mask 
alternative_cb_end

.endm



/*

 * Convert a kernel image address to a PA

 * reg: kernel address to be converted in place

 * tmp: temporary register

 *

 * The actual code generation takes place in kvm_get_kimage_voffset, and

 * the instructions below are only there to reserve the space and

 * perform the register allocation (kvm_get_kimage_voffset uses the

 * specific registers encoded in the instructions).

 */

.macro kimg_pa reg, tmp

alternative_cb kvm_get_kimage_voffset

	movz	\tmp, #0

	movk	\tmp, #0, lsl #16

	movk	\tmp, #0, lsl #32

	movk	\tmp, #0, lsl #48

alternative_cb_end



	/* reg = __pa(reg) */

	sub	\reg, \reg, \tmp

.endm



#else



#include <linux/pgtable.h>

arch/arm64/kernel/image-vars.h

+1 −3
Original line number Diff line number Diff line
@@ -65,13 +65,11 @@ __efistub__ctype = _ctype; 
KVM_NVHE_ALIAS(kvm_patch_vector_branch);

KVM_NVHE_ALIAS(kvm_update_va_mask);

KVM_NVHE_ALIAS(kvm_update_kimg_phys_offset);

KVM_NVHE_ALIAS(kvm_get_kimage_voffset);



/* Global kernel state accessed by nVHE hyp code. */

KVM_NVHE_ALIAS(kvm_vgic_global_state);



/* Kernel constant needed to compute idmap addresses. */

KVM_NVHE_ALIAS(kimage_voffset);



/* Kernel symbols used to call panic() from nVHE hyp code (via ERET). */

KVM_NVHE_ALIAS(__hyp_panic_string);

KVM_NVHE_ALIAS(panic);

arch/arm64/kvm/hyp/nvhe/host.S

+1 −4
Original line number Diff line number Diff line
@@ -115,10 +115,7 @@ SYM_FUNC_END(__hyp_do_panic) 
	 * 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

	kimg_pa x5, x6

	br	x5

.L__vect_end\@:

.if ((.L__vect_end\@ - .L__vect_start\@) > 0x80)

arch/arm64/kvm/va_layout.c

+6 −0
Original line number Diff line number Diff line
@@ -251,3 +251,9 @@ void kvm_update_kimg_phys_offset(struct alt_instr *alt, 
{

	generate_mov_q(kimage_voffset + PHYS_OFFSET, origptr, updptr, nr_inst);

}



void kvm_get_kimage_voffset(struct alt_instr *alt,

			    __le32 *origptr, __le32 *updptr, int nr_inst)

{

	generate_mov_q(kimage_voffset, origptr, updptr, nr_inst);

}