From: Andrew Scull ascull@google.com

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: af42f20480bf1 ("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 --- arch/arm64/kvm/hyp-init.S | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/hyp-init.S b/arch/arm64/kvm/hyp-init.S index 6e6ed5581eed..e76c0e89d48e 100644 --- a/arch/arm64/kvm/hyp-init.S +++ b/arch/arm64/kvm/hyp-init.S @@ -136,11 +136,15 @@ SYM_CODE_START(__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 mov_q x6, SCTLR_ELx_FLAGS bic x5, x5, x6 // Clear SCTL_M and etc @@ -151,7 +155,6 @@ reset: /* Install stub vectors */ adr_l x5, __hyp_stub_vectors msr vbar_el2, x5 - mov x0, xzr eret

1: /* Bad stub call */