>>> On 20.11.18 at 17:01, <roger....@citrix.com> wrote:
> Current logic to handle long running operations is flawed because it
> doesn't prevent the guest vcpu from running. Fix this by raising a
> scheduler softirq when preemption is required, so that the do_softirq
> call in the guest entry path performs a rescheduling. Also move the
> call to vpci_process_pending into handle_hvm_io_completion, together
> with the IOREQ code that handles pending IO instructions.
>
> Note that a scheduler softirq is also raised when the long running
> operation is queued in order to prevent the guest vcpu from resuming
> execution.
>
> Signed-off-by: Roger Pau Monné <roger....@citrix.com>
> ---
> Cc: Paul Durrant <paul.durr...@citrix.com>
> Cc: Jan Beulich <jbeul...@suse.com>
> Cc: Andrew Cooper <andrew.coop...@citrix.com>
> Cc: Wei Liu <wei.l...@citrix.com>
> Cc: George Dunlap <george.dun...@eu.citrix.com>
> Cc: Ian Jackson <ian.jack...@eu.citrix.com>
> Cc: Julien Grall <julien.gr...@arm.com>
> Cc: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
> Cc: Stefano Stabellini <sstabell...@kernel.org>
> Cc: Tim Deegan <t...@xen.org>
> ---
> Changes since v4:
> - Add a comment to clarify defer_map raising a scheduler softirq.
> - Reword commit message.
> - Raise the scheduler softirq in handle_hvm_io_completion rather than
> vpci_process_pending.
>
> Changes since v3:
> - Don't use a tasklet.
> ---
> xen/arch/x86/hvm/ioreq.c | 9 ++++++---
Paul - I'll take the liberty and reinstate your v4 R-b for v5.
Jan
> xen/drivers/vpci/header.c | 5 +++++
> 2 files changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/xen/arch/x86/hvm/ioreq.c b/xen/arch/x86/hvm/ioreq.c
> index a56d634f31..71f23227e6 100644
> --- a/xen/arch/x86/hvm/ioreq.c
> +++ b/xen/arch/x86/hvm/ioreq.c
> @@ -85,9 +85,6 @@ bool hvm_io_pending(struct vcpu *v)
> struct hvm_ioreq_server *s;
> unsigned int id;
>
> - if ( has_vpci(d) && vpci_process_pending(v) )
> - return true;
> -
> FOR_EACH_IOREQ_SERVER(d, id, s)
> {
> struct hvm_ioreq_vcpu *sv;
> @@ -186,6 +183,12 @@ bool handle_hvm_io_completion(struct vcpu *v)
> enum hvm_io_completion io_completion;
> unsigned int id;
>
> + if ( has_vpci(d) && vpci_process_pending(v) )
> + {
> + raise_softirq(SCHEDULE_SOFTIRQ);
> + return false;
> + }
> +
> FOR_EACH_IOREQ_SERVER(d, id, s)
> {
> struct hvm_ioreq_vcpu *sv;
> diff --git a/xen/drivers/vpci/header.c b/xen/drivers/vpci/header.c
> index 39dffb21fb..c9bdc2ced3 100644
> --- a/xen/drivers/vpci/header.c
> +++ b/xen/drivers/vpci/header.c
> @@ -184,6 +184,11 @@ static void defer_map(struct domain *d, struct pci_dev
> *pdev,
> curr->vpci.mem = mem;
> curr->vpci.cmd = cmd;
> curr->vpci.rom_only = rom_only;
> + /*
> + * Raise a scheduler softirq in order to prevent the guest from
> resuming
> + * execution with pending mapping operations.
> + */
> + raise_softirq(SCHEDULE_SOFTIRQ);
> }
>
> static int modify_bars(const struct pci_dev *pdev, uint16_t cmd, bool
> rom_only)
> --
> 2.19.1
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
