From: Peter Maydell <peter.mayd...@linaro.org> If we're booting a Linux kernel directly into Non-Secure state on a CPU which has Secure state, then make sure we set the NSACR CP11 and CP10 bits, so that Non-Secure is allowed to access the FPU. Otherwise an AArch32 kernel will UNDEF as soon as it tries to use the FPU.
It used to not matter that we didn't do this until commit fc1120a7f5f2d4b6, where we implemented actually honouring these NSACR bits. The problem only exists for CPUs where EL3 is AArch32; the equivalent AArch64 trap bits are in CPTR_EL3 and are "0 to not trap, 1 to trap", so the reset value of the register permits NS access, unlike NSACR. Fixes: fc1120a7f5 Fixes: https://bugs.launchpad.net/qemu/+bug/1844597 Cc: qemu-sta...@nongnu.org Signed-off-by: Peter Maydell <peter.mayd...@linaro.org> Reviewed-by: Richard Henderson <richard.hender...@linaro.org> Message-id: 20190920174039.3916-1-peter.mayd...@linaro.org (cherry picked from commit ece628fcf69cbbd4b3efb6fbd203af07609467a2) Signed-off-by: Michael Roth <mdr...@linux.vnet.ibm.com> --- hw/arm/boot.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/hw/arm/boot.c b/hw/arm/boot.c index c2b89b3bb9..fc4e021a38 100644 --- a/hw/arm/boot.c +++ b/hw/arm/boot.c @@ -754,6 +754,8 @@ static void do_cpu_reset(void *opaque) (cs != first_cpu || !info->secure_board_setup)) { /* Linux expects non-secure state */ env->cp15.scr_el3 |= SCR_NS; + /* Set NSACR.{CP11,CP10} so NS can access the FPU */ + env->cp15.nsacr |= 3 << 10; } } -- 2.17.1
