From: Julien Grall Date: Mon, 12 Mar 2018 13:19:35 +0000 (+0000) Subject: xen/arm: Relax ARM_SMCCC_ARCH_WORKAROUND_1 discovery X-Git-Tag: archive/raspbian/4.11.1-1+rpi1~1^2~66^2~386 X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=6b270fae7ad462687550a875f714bff18d764416;p=xen.git xen/arm: Relax ARM_SMCCC_ARCH_WORKAROUND_1 discovery A recent update to the ARM SMCCC_ARCH_WORKAROUND_1 specification (see [1]) allows firmware to return a non zero, positive value, to describe that although the mitigation is implemented at the higher exception level, the CPU on which the call is made is not affected. Relax the check on the return value from ARM_WORKAROUND_1 so that we only error out if the returned value is negative. [1] https://developer.arm.com/support/security-update/downloads "Firmware interfaces for mitigating CVE-2017-5715 System Software on Arm Systems" Signed-off-by: Julien Grall Reviewed-by: Stefano Stabellini --- diff --git a/xen/arch/arm/cpuerrata.c b/xen/arch/arm/cpuerrata.c index 4eb1567589..1baa20654b 100644 --- a/xen/arch/arm/cpuerrata.c +++ b/xen/arch/arm/cpuerrata.c @@ -168,7 +168,8 @@ static int enable_smccc_arch_workaround_1(void *data) arm_smccc_1_1_smc(ARM_SMCCC_ARCH_FEATURES_FID, ARM_SMCCC_ARCH_WORKAROUND_1_FID, &res); - if ( res.a0 != ARM_SMCCC_SUCCESS ) + /* The return value is in the lower 32-bits. */ + if ( (int)res.a0 < 0 ) goto warn; return !install_bp_hardening_vec(entry,__smccc_workaround_1_smc_start,