On Thu, Feb 26, 2015 at 08:08:15AM +0000, Wu, Feng wrote: > > > > -----Original Message----- > > From: Marcelo Tosatti [mailto:mtosa...@redhat.com] > > Sent: Thursday, February 26, 2015 5:50 AM > > To: Wu, Feng > > Cc: t...@linutronix.de; mi...@redhat.com; h...@zytor.com; x...@kernel.org; > > g...@kernel.org; pbonz...@redhat.com; dw...@infradead.org; > > j...@8bytes.org; alex.william...@redhat.com; jiang....@linux.intel.com; > > eric.au...@linaro.org; linux-kernel@vger.kernel.org; > > io...@lists.linux-foundation.org; k...@vger.kernel.org > > Subject: Re: [v3 24/26] KVM: Update Posted-Interrupts Descriptor when vCPU > > is blocked > > > > On Fri, Dec 12, 2014 at 11:14:58PM +0800, Feng Wu wrote: > > > This patch updates the Posted-Interrupts Descriptor when vCPU > > > is blocked. > > > > > > pre-block: > > > - Add the vCPU to the blocked per-CPU list > > > - Clear 'SN' > > > - Set 'NV' to POSTED_INTR_WAKEUP_VECTOR > > > > > > post-block: > > > - Remove the vCPU from the per-CPU list > > > > > > Signed-off-by: Feng Wu <feng...@intel.com> > > > --- > > > > Don't see this is needed, can use the existing POSTED_INTR_VECTOR: > > > > If in guest mode, IPI will be handled in VMX non-root by performed > > PIR->IRR transfer. > > > > If outside guest mode, POSTED_INTR_VECTOR IPI will be handled by host > > which can wakeup the guest (in case it is halted). > > Please see the following scenario: > > 1. vCPU0 is running on pCPU0 > 2. vCPU0 is halted and vCPU1 is currently running on pCPU0 > 3. An interrupt occurs for vCPU0, if we still use POSTED_INTR_VECTOR > for vCPU0, the notification event for vCPU0 (the event will go to pCPU1) > will be consumed by vCPU1 incorrectly. The worst case is that vCPU0 > will never be woken up again since the wakeup event for it is always > consumed by other vCPUs incorrectly. > > Thanks, > Feng
Ouch, yes. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
