Re: [PATCH 2/3] KVM: PPC: Book3S HV: XIVE: do not test the EQ flag validity when resetting

Greg Kurz
2019-05-20T11:42:29Z

On Mon, 20 May 2019 09:15:13 +0200
Cédric Le Goater <clg@kaod.org> wrote:

> When a CPU is hot-unplugged, the EQ is deconfigured using a zero size
> and a zero address. In this case, there is no need to check the flag
> and queue size validity. Move the checks after the queue reset code
> section to fix CPU hot-unplug.
>
> Reported-by: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
> Tested-by: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> ---

Reviewed-by: Greg Kurz <groug@kaod.org>

> arch/powerpc/kvm/book3s_xive_native.c | 36 +++++++++++++--------------
> 1 file changed, 18 insertions(+), 18 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_xive_native.c b/arch/powerpc/kvm/book3s_xive_native.c
> index 796d86549cfe..3fdea6bf4e97 100644
> --- a/arch/powerpc/kvm/book3s_xive_native.c
> +++ b/arch/powerpc/kvm/book3s_xive_native.c
> @@ -565,24 +565,6 @@ static int kvmppc_xive_native_set_queue_config(struct kvmppc_xive *xive,
> __func__, server, priority, kvm_eq.flags,
> kvm_eq.qshift, kvm_eq.qaddr, kvm_eq.qtoggle, kvm_eq.qindex);
>
> - /*
> - * sPAPR specifies a "Unconditional Notify (n) flag" for the
> - * H_INT_SET_QUEUE_CONFIG hcall which forces notification
> - * without using the coalescing mechanisms provided by the
> - * XIVE END ESBs. This is required on KVM as notification
> - * using the END ESBs is not supported.
> - */
> - if (kvm_eq.flags != KVM_XIVE_EQ_ALWAYS_NOTIFY) {
> - pr_err("invalid flags %d\n", kvm_eq.flags);
> - return -EINVAL;
> - }
> -
> - rc = xive_native_validate_queue_size(kvm_eq.qshift);
> - if (rc) {
> - pr_err("invalid queue size %d\n", kvm_eq.qshift);
> - return rc;
> - }
> -
> /* reset queue and disable queueing */
> if (!kvm_eq.qshift) {
> q->guest_qaddr = 0;
> @@ -604,6 +586,24 @@ static int kvmppc_xive_native_set_queue_config(struct kvmppc_xive *xive,
> return 0;
> }
>
> + /*
> + * sPAPR specifies a "Unconditional Notify (n) flag" for the
> + * H_INT_SET_QUEUE_CONFIG hcall which forces notification
> + * without using the coalescing mechanisms provided by the
> + * XIVE END ESBs. This is required on KVM as notification
> + * using the END ESBs is not supported.
> + */
> + if (kvm_eq.flags != KVM_XIVE_EQ_ALWAYS_NOTIFY) {
> + pr_err("invalid flags %d\n", kvm_eq.flags);
> + return -EINVAL;
> + }
> +
> + rc = xive_native_validate_queue_size(kvm_eq.qshift);
> + if (rc) {
> + pr_err("invalid queue size %d\n", kvm_eq.qshift);
> + return rc;
> + }
> +
> if (kvm_eq.qaddr & ((1ull << kvm_eq.qshift) - 1)) {
> pr_err("queue page is not aligned %llx/%llx\n", kvm_eq.qaddr,
> 1ull << kvm_eq.qshift);