> -----Original Message-----
> From: Roger Pau Monne [mailto:roger....@citrix.com]
> Sent: 14 November 2018 11:58
> To: xen-devel@lists.xenproject.org
> Cc: Roger Pau Monne <roger....@citrix.com>; Paul Durrant
> <paul.durr...@citrix.com>; Jan Beulich <jbeul...@suse.com>; Andrew Cooper
> <andrew.coop...@citrix.com>; Wei Liu <wei.l...@citrix.com>; George Dunlap
> <george.dun...@citrix.com>; Ian Jackson <ian.jack...@citrix.com>; Julien
> Grall <julien.gr...@arm.com>; Konrad Rzeszutek Wilk
> <konrad.w...@oracle.com>; Stefano Stabellini <sstabell...@kernel.org>; Tim
> (Xen.org) <t...@xen.org>
> Subject: [PATCH v4 2/5] vpci: fix deferral of long operations
>
> Current logic to handle long running operations has two flaws:
>
> - hvm_io_pending is only used by Intel code, fix this by moving the
> call to vpci_process_pending into handle_hvm_io_completion.
> - Raise a scheduler softirq when preemption is required. The
> do_softirq calls in the SVM/VMX guest entry points will make sure
> the guest vcpu is not restarted until all the pending work is
> finished.
>
> Signed-off-by: Roger Pau Monné <roger....@citrix.com>
Reviewed-by: Paul Durrant <paul.durr...@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 v3:
> - Don't use a tasklet.
> ---
> xen/arch/x86/hvm/ioreq.c | 6 +++---
> xen/drivers/vpci/header.c | 4 ++++
> 2 files changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/xen/arch/x86/hvm/ioreq.c b/xen/arch/x86/hvm/ioreq.c
> index e2e755a8a1..4c4b33e220 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 +183,9 @@ 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) )
> + 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 162d51f7e2..720dec07fa 100644
> --- a/xen/drivers/vpci/header.c
> +++ b/xen/drivers/vpci/header.c
> @@ -127,7 +127,10 @@ bool vpci_process_pending(struct vcpu *v)
> int rc = rangeset_consume_ranges(v->vpci.mem, map_range, &data);
>
> if ( rc == -ERESTART )
> + {
> + raise_softirq(SCHEDULE_SOFTIRQ);
> return true;
> + }
>
> spin_lock(&v->vpci.pdev->vpci->lock);
> /* Disable memory decoding unconditionally on failure. */
> @@ -182,6 +185,7 @@ 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_softirq(SCHEDULE_SOFTIRQ);
> }
>
> static int modify_bars(const struct pci_dev *pdev, uint16_t cmd, bool
> rom_only)
> --
> 2.19.1
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