From: Peter Maydell <peter.maydell@linaro.org>
Date: Fri, 24 Jan 2025 16:27:23 +0000 (+0000)
Subject: target/arm: arm_reset_sve_state() should set FPSR, not FPCR
X-Git-Tag: v9.2.1~7
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=c806bbe8c161d0524648fc6fe024ceefbb833071;p=thirdparty%2Fqemu.git

target/arm: arm_reset_sve_state() should set FPSR, not FPCR

The pseudocode ResetSVEState() does:
    FPSR = ZeroExtend(0x0800009f<31:0>, 64);
but QEMU's arm_reset_sve_state() called vfp_set_fpcr() by accident.

Before the advent of FEAT_AFP, this was only setting a collection of
RES0 bits, which vfp_set_fpsr() would then ignore, so the only effect
was that we didn't actually set the FPSR the way we are supposed to
do.  Once FEAT_AFP is implemented, setting the bottom bits of FPSR
will change the floating point behaviour.

Call vfp_set_fpsr(), as we ought to.

(Note for stable backports: commit 7f2a01e7368f9 moved this function
from sme_helper.c to helper.c, but it had the same bug before the
move too.)

Cc: qemu-stable@nongnu.org
Fixes: f84734b87461 ("target/arm: Implement SMSTART, SMSTOP")
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250124162836.2332150-4-peter.maydell@linaro.org
(cherry picked from commit 1edc3d43f20df0d04f8d00b906ba19fed37512a5)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
---

diff --git a/target/arm/helper.c b/target/arm/helper.c
index f38eb054c0..fcb13fe87e 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -7362,7 +7362,7 @@ static void arm_reset_sve_state(CPUARMState *env)
     memset(env->vfp.zregs, 0, sizeof(env->vfp.zregs));
     /* Recall that FFR is stored as pregs[16]. */
     memset(env->vfp.pregs, 0, sizeof(env->vfp.pregs));
-    vfp_set_fpcr(env, 0x0800009f);
+    vfp_set_fpsr(env, 0x0800009f);
 }
 
 void aarch64_set_svcr(CPUARMState *env, uint64_t new, uint64_t mask)