On Wed Jun 5, 2024 at 9:39 PM AEST, Gautam Menghani wrote:
Doorbell emulation is broken for KVM on PAPR guests as support for DPDES was not added in the initial patch series. Due to this, a KVM on PAPR guest with SMT > 1 cannot be booted with the XICS interrupt controller as doorbells are setup in the initial probe path when using XICS (pSeries_smp_probe()).
Command to replicate the above bug:
qemu-system-ppc64 \ -drive file=rhel.qcow2,format=qcow2 \ -m 20G \ -smp 8,cores=1,threads=8 \ -cpu host \ -nographic \ -machine pseries,ic-mode=xics -accel kvm
Add doorbell state handling support in the host KVM code to fix doorbell emulation.
Reviewed-by: Nicholas Piggin npiggin@gmail.com
Fixes: 19d31c5f1157 ("KVM: PPC: Add support for nestedv2 guests") Cc: stable@vger.kernel.org # v6.7 Signed-off-by: Gautam Menghani gautam@linux.ibm.com
arch/powerpc/kvm/book3s_hv.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 35cb014a0c51..21c69647d27c 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -4116,6 +4116,11 @@ static int kvmhv_vcpu_entry_nestedv2(struct kvm_vcpu *vcpu, u64 time_limit, int trap; long rc;
- if (vcpu->arch.doorbell_request) {
vcpu->arch.doorbell_request = 0;kvmppc_set_dpdes(vcpu, 1);- }
- io = &vcpu->arch.nestedv2_io;
msr = mfmsr();