在2024年5月30日五月 上午7:49，Bibo Mao写道：
Loongson Binary Translation (LBT) is used to accelerate binary
translation, which contains 4 scratch registers (scr0 to scr3), x86/ARM
eflags (eflags) and x87 fpu stack pointer (ftop).
Now LBT feature is added in kvm mode, not supported in TCG mode since
it is not emulated. Feature variable lbt is added with OnOffAuto type,
If lbt feature is not supported with KVM host, it reports error if there
is lbt=on command line.
If there is no any command line about lbt parameter, it checks whether
KVM host supports lbt feature and set the corresponding value in cpucfg.
Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Hi Bibo,
I was going across recent LoongArch changes and this comes into my attention:
---
target/loongarch/cpu.c | 53 +++++++++++++++++++++++++++
target/loongarch/cpu.h | 6 +++
target/loongarch/kvm/kvm.c | 26 +++++++++++++
target/loongarch/kvm/kvm_loongarch.h | 16 ++++++++
target/loongarch/loongarch-qmp-cmds.c | 2 +-
5 files changed, 102 insertions(+), 1 deletion(-)
diff --git a/target/loongarch/cpu.c b/target/loongarch/cpu.c
index b5c1ec94af..14265b6667 100644
--- a/target/loongarch/cpu.c
+++ b/target/loongarch/cpu.c
@@ -571,6 +571,30 @@ static void loongarch_cpu_disas_set_info(CPUState
*s, disassemble_info *info)
info->print_insn = print_insn_loongarch;
}
+static void loongarch_cpu_check_lbt(CPUState *cs, Error **errp)
+{
+ CPULoongArchState *env = cpu_env(cs);
+ LoongArchCPU *cpu = LOONGARCH_CPU(cs);
+ bool kvm_supported;
+
+ kvm_supported = kvm_feature_supported(cs, LOONGARCH_FEATURE_LBT);
IMHO if there is no global states that should be saved/restored VM wise,
this should be handled at per CPU level, preferably with CPUCFG flags hint.
We should minimize non-privilege KVM feature bits to prevent hindering
asymmetry ISA system.