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Date: Fri, 8 Dec 2023 16:28:35 -0800
From: Jacob Pan <jacob.jun.pan@linux.intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>, X86 Kernel <x86@kernel.org>,
 iommu@lists.linux.dev, Lu Baolu <baolu.lu@linux.intel.com>,
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 maz@kernel.org, peterz@infradead.org, seanjc@google.com, Robin Murphy
 <robin.murphy@arm.com>, jacob.jun.pan@linux.intel.com
Subject: Re: [PATCH RFC 01/13] x86: Move posted interrupt descriptor out of
 vmx code
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Hi Thomas,

On Fri, 08 Dec 2023 10:31:20 +0100, Thomas Gleixner <tglx@linutronix.de>
wrote:

> On Thu, Dec 07 2023 at 20:54, Jacob Pan wrote:
> > On Wed, 06 Dec 2023 17:33:28 +0100, Thomas Gleixner <tglx@linutronix.de>
> > wrote:  
> >> On Sat, Nov 11 2023 at 20:16, Jacob Pan wrote:
> >> 	u32			rsvd[6];
> >> } __aligned(64);
> >>   
> > It seems bit-fields cannot pass type check. I got these compile error.  
> 
> And why are you telling me that instead if simply fixing it?
I guess we can fix it like this to use the new bitfields:

 void intel_posted_msi_init(void)
 {
-       this_cpu_write(posted_interrupt_desc.nv, POSTED_MSI_NOTIFICATION_VECTOR);
-       this_cpu_write(posted_interrupt_desc.ndst, this_cpu_read(x86_cpu_to_apicid));
+       struct pi_desc *pid = this_cpu_ptr(&posted_interrupt_desc);
+
+       pid->nv = POSTED_MSI_NOTIFICATION_VECTOR;
+       pid->ndst = this_cpu_read(x86_cpu_to_apicid);

It is init time, no IOMMU posting yet. So no need for atomics.


Thanks,

Jacob