File hw-arm-boot.c-Set-NSACR.-CP11-CP10-for-N.patch of Package qemu

Overview Repositories Revisions Requests Users Attributes Meta

File hw-arm-boot.c-Set-NSACR.-CP11-CP10-for-N.patch of Package qemu (Revision 2b2ec40cac84f0f7228f35537d83fcee)

Currently displaying revision 2b2ec40cac84f0f7228f35537d83fcee , Show latest

From: Peter Maydell <peter.maydell@linaro.org>
Date: Fri, 20 Sep 2019 18:40:39 +0100
Subject: hw/arm/boot.c: Set NSACR.{CP11,CP10} for NS kernel boots

Git-commit: ece628fcf69cbbd4b3efb6fbd203af07609467a2

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-stable@nongnu.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20190920174039.3916-1-peter.maydell@linaro.org
Signed-off-by: Bruce Rogers <brogers@suse.com>
---
 hw/arm/boot.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/hw/arm/boot.c b/hw/arm/boot.c
index c2b89b3bb9b6b92b0293d859712e..fc4e021a38a6bc1e5e2aa5b5876c 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;
                 }
             }

Places

File hw-arm-boot.c-Set-NSACR.-CP11-CP10-for-N.patch of Package qemu (Revision 2b2ec40cac84f0f7228f35537d83fcee)

Places