From 3e568fa9e19ccefcfd0d3056cb80d0b15f2bf0f7 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Roger=20Pau=20Monn=C3=A9?= Date: Mon, 26 Nov 2018 15:41:12 +0100 Subject: [PATCH] vpci: fix deferral of long operations MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Paul Durrant Reviewed-by: Jan Beulich --- xen/arch/x86/hvm/ioreq.c | 9 ++++++--- xen/drivers/vpci/header.c | 6 ++++++ 2 files changed, 12 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..92c00b68aa 100644 --- a/xen/drivers/vpci/header.c +++ b/xen/drivers/vpci/header.c @@ -184,6 +184,12 @@ 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, to trigger the invocation + * of vpci_process_pending(). + */ + raise_softirq(SCHEDULE_SOFTIRQ); } static int modify_bars(const struct pci_dev *pdev, uint16_t cmd, bool rom_only) -- 2.30.2