From f7767ca301796334f74b9b642b395a4bd3e3dbac Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Mon, 4 Dec 2023 13:34:16 +0000 Subject: [PATCH] target/arm: Disable SME if SVE is disabled There is no architectural requirement that SME implies SVE, but our implementation currently assumes it. (FEAT_SME_FA64 does imply SVE.) So if you try to run a CPU with eg "-cpu max,sve=off" you quickly run into an assert when the guest tries to write to SMCR_EL1: #6 0x00007ffff4b38e96 in __GI___assert_fail (assertion=0x5555566e69cb "sm", file=0x5555566e5b24 "../../target/arm/helper.c", line=6865, function=0x5555566e82f0 <__PRETTY_FUNCTION__.31> "sve_vqm1_for_el_sm") at ./assert/assert.c:101 #7 0x0000555555ee33aa in sve_vqm1_for_el_sm (env=0x555557d291f0, el=2, sm=false) at ../../target/arm/helper.c:6865 #8 0x0000555555ee3407 in sve_vqm1_for_el (env=0x555557d291f0, el=2) at ../../target/arm/helper.c:6871 #9 0x0000555555ee3724 in smcr_write (env=0x555557d291f0, ri=0x555557da23b0, value=2147483663) at ../../target/arm/helper.c:6995 #10 0x0000555555fd1dba in helper_set_cp_reg64 (env=0x555557d291f0, rip=0x555557da23b0, value=2147483663) at ../../target/arm/tcg/op_helper.c:839 #11 0x00007fff60056781 in code_gen_buffer () Avoid this unsupported and slightly odd combination by disabling SME when SVE is not present. Cc: qemu-stable@nongnu.org Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2005 Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson Message-id: 20231127173318.674758-1-peter.maydell@linaro.org --- target/arm/cpu.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/target/arm/cpu.c b/target/arm/cpu.c index 25e9d2ae7b8..efb22a87f9e 100644 --- a/target/arm/cpu.c +++ b/target/arm/cpu.c @@ -1743,6 +1743,16 @@ void arm_cpu_finalize_features(ARMCPU *cpu, Error **errp) return; } + /* + * FEAT_SME is not architecturally dependent on FEAT_SVE (unless + * FEAT_SME_FA64 is present). However our implementation currently + * assumes it, so if the user asked for sve=off then turn off SME also. + * (KVM doesn't currently support SME at all.) + */ + if (cpu_isar_feature(aa64_sme, cpu) && !cpu_isar_feature(aa64_sve, cpu)) { + object_property_set_bool(OBJECT(cpu), "sme", false, &error_abort); + } + arm_cpu_sme_finalize(cpu, &local_err); if (local_err != NULL) { error_propagate(errp, local_err);