Commit 20f40462 authored Jul 06, 2020 by Andrew Scull Committed by Greg Kroah-Hartman Jul 22, 2020

KVM: arm64: Stop clobbering x0 for HVC_SOFT_RESTART



commit b9e10d4a6c9f5cbe6369ce2c17ebc67d2e5a4be5 upstream.

HVC_SOFT_RESTART is given values for x0-2 that it should installed
before exiting to the new address so should not set x0 to stub HVC
success or failure code.

Fixes: af42f204 ("arm64: hyp-stub: Zero x0 on successful stub handling")
Cc: stable@vger.kernel.org
Signed-off-by: Andrew Scull <ascull@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200706095259.1338221-1-ascull@google.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 6a47a77c

arch/arm64/kvm/hyp-init.S

+7 −4

Original line number	Diff line number	Diff line
		@@ -147,11 +147,15 @@ ENTRY(__kvm_handle_stub_hvc)

		1: cmp x0, #HVC_RESET_VECTORS
		b.ne 1f
		reset:

		/*
		* Reset kvm back to the hyp stub. Do not clobber x0-x4 in
		* case we coming via HVC_SOFT_RESTART.
		* Set the HVC_RESET_VECTORS return code before entering the common
		* path so that we do not clobber x0-x2 in case we are coming via
		* HVC_SOFT_RESTART.
		*/
		mov x0, xzr
		reset:
		/* Reset kvm back to the hyp stub. */
		mrs x5, sctlr_el2
		ldr x6, =SCTLR_ELx_FLAGS
		bic x5, x5, x6 // Clear SCTL_M and etc
		@@ -162,7 +166,6 @@ reset:
		/* Install stub vectors */
		adr_l x5, __hyp_stub_vectors
		msr vbar_el2, x5
		mov x0, xzr
		eret

		1: /* Bad stub call */