> -----Original Message----- > From: Marcelo Tosatti [mailto:[email protected]] > Sent: Thursday, February 26, 2015 5:50 AM > To: Wu, Feng > Cc: [email protected]; [email protected]; [email protected]; [email protected]; > [email protected]; [email protected]; [email protected]; > [email protected]; [email protected]; [email protected]; > [email protected]; [email protected]; > [email protected]; [email protected] > 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 <[email protected]> > > --- > > 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
