> From: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx> > Sent: Wednesday, March 7, 2018 04:35 > On Tue, Mar 06, 2018 at 06:21:56PM +0000, Dexuan Cui wrote: > > 1. With the patch "x86/vector/msi: Switch to global reservation mode" > > (4900be8360), the recent v4.15 and newer kernels always hang for 1-vCPU > > Hyper-V VM with SR-IOV. This is because when we reach > hv_compose_msi_msg() > > by request_irq() -> request_threaded_irq() -> __setup_irq()->irq_startup() > > -> __irq_startup() -> irq_domain_activate_irq() -> ... -> > > msi_domain_activate() -> ... -> hv_compose_msi_msg(), local irq is > > disabled in __setup_irq(). > > > > Fix this by polling the channel. > > > > 2. If the host is ejecting the VF device before we reach > > hv_compose_msi_msg(), in a UP VM, we can hang in hv_compose_msi_msg() > > forever, because at this time the host doesn't respond to the > > CREATE_INTERRUPT request. This issue also happens to old kernels like > > v4.14, v4.13, etc. > > If you are fixing a problem you should report what commit you are fixing > with a Fixes: tag and add a CC: stable@xxxxxxxxxxxxxxx to the commit log > to send it to stable kernels to which it should be applied; mentioning > kernel versions in the commit log is useless and should be omitted. Hi Lorenzo, Thanks for your comments! This patch does have a "Cc: stable@xxxxxxxxxxxxxxx" in the sign-off area. :-) Here the patch is made to resolve 2 issues: #1 is triggered by the x86 global reservation mode (4900be8360) patch. 4900be8360 in itself is good. It's just that drivers/pci/host/pci-hyperv.c should be fixed. #2 is a longstanding issue since the first day the pci-hyperv driver was accepted into the kernel. So IMO actually we don't really need to add a Fixes: tag, which is usually used to specify a specific commit that introduces a bug that is being fixed. > Side note: you should not have stable@xxxxxxxxxxxxxxx in the email > addresses CC list you are sending the patches to (you mark patches for > stable by adding an appropriate CC tag in the commit log). Sorry, I didn't know this, but actually I didn't add stable@xxxxxxxxxxxxxxx manually. Instead I used "git send-email" to send this patchset, and it told me "The Cc list above has been expanded by additional addresses found in the patch commit message." I didn't find a way to disable this behavior of "git send-email" by checking its manual and googling it. This is strange. > Here: > > git.kernel.org/.../Documentation/process/stable-kernel-rules.rst > > Last but not least, most of the patches in this series do not justify > sending them to stable kernels at all so you should remove the > corresponding tag from the patches. I hope at least these 2 patches can go into the stable kernels: [PATCH v3 3/6] PCI: hv: serialize the present/eject work items [PATCH v3 6/6] PCI: hv: fix 2 hang issues in hv_compose_msi_msg() Especially the second one, which fixes a real hang issue for UP virtual machines running v4.15 and newer. And, IMO the patches are small enough (<100 lines) , but definitely the maintainers make the final call. > > Thanks, > Lorenzo > > > Fix this by polling the channel for the PCI_EJECT message and > > hpdev->state, and by checking the PCI vendor ID. > > > > Note: actually the above issues also happen to a SMP VM, if > > "hbus->hdev->channel->target_cpu == smp_processor_id()" is true. > > > > Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx> > > Tested-by: Adrian Suhov <v-adsuho@xxxxxxxxxxxxx> > > Tested-by: Chris Valean <v-chvale@xxxxxxxxxxxxx> > > Cc: stable@xxxxxxxxxxxxxxx > > Cc: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx> > > Cc: K. Y. Srinivasan <kys@xxxxxxxxxxxxx> > > Cc: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> > > Cc: Jack Morgenstein <jackm@xxxxxxxxxxxx> > > --- > > drivers/pci/host/pci-hyperv.c | 58 Thanks, -- Dexuan
