On Wed, 18 Sept 2024 at 14:06, Heinrich Schuchardt <heinrich.schuchardt@xxxxxxxxxxxxx> wrote: > Thanks Peter for looking into this. > > QEMU's cpu_synchronize_all_post_init() and > do_kvm_cpu_synchronize_post_reset() both end up in > kvm_arch_put_registers() and that is long after Linux > kvm_arch_vcpu_create() has been setting some FPU state. See the output > below. > > kvm_arch_put_registers() copies the CSRs by calling > kvm_riscv_put_regs_csr(). Here we can find: > > KVM_RISCV_SET_CSR(cs, env, sstatus, env->mstatus); > > This call enables or disables the FPU according to the value of > env->mstatus. > > So we need to set the desired state of the floating point unit in QEMU. > And this is what the current patch does both for TCG and KVM. If it does this for both TCG and KVM then I don't understand this bit from the commit message: # Without this patch EDK II with TLS enabled crashes when hitting the first # floating point instruction while running QEMU with --accel kvm and runs # fine with --accel tcg. Shouldn't this guest crash the same way with both KVM and TCG without this patch, because the FPU state is the same for both? -- PMM
