linux-kernel - Re: [RFC 02/14] x86/apic: Initialize Secure AVIC APIC backing page

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Message-ID: <02e72165-a32b-48da-9eff-199c52cfacf8@amd.com>
Date: Thu, 24 Oct 2024 08:54:09 +0530
From: Neeraj Upadhyay <Neeraj.Upadhyay@....com>
To: Borislav Petkov <bp@...en8.de>
Cc: linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
 dave.hansen@...ux.intel.com, Thomas.Lendacky@....com, nikunj@....com,
 Santosh.Shukla@....com, Vasant.Hegde@....com, Suravee.Suthikulpanit@....com,
 David.Kaplan@....com, x86@...nel.org, hpa@...or.com, peterz@...radead.org,
 seanjc@...gle.com, pbonzini@...hat.com, kvm@...r.kernel.org
Subject: Re: [RFC 02/14] x86/apic: Initialize Secure AVIC APIC backing page



On 10/23/2024 10:06 PM, Borislav Petkov wrote:
> On Fri, Sep 13, 2024 at 05:06:53PM +0530, Neeraj Upadhyay wrote:
>> @@ -61,8 +65,30 @@ static void x2apic_savic_send_IPI_mask_allbutself(const struct cpumask *mask, in
>>  	__send_IPI_mask(mask, vector, APIC_DEST_ALLBUT);
>>  }
>>  
>> +static void x2apic_savic_setup(void)
>> +{
>> +	void *backing_page;
>> +	enum es_result ret;
>> +	unsigned long gpa;
>> +
>> +	if (this_cpu_read(savic_setup_done))
> 
> I'm sure you can get rid of that silly bool. Like check the apic_backing_page
> pointer instead and use that pointer to verify whether the per-CPU setup has
> been done successfully.
> 

Ok agree. In this patch version, APIC backing page allocation for all CPUs is done in
x2apic_savic_probe(). This is done to group the allocation together, so that these
backing pages are mapped using single 2M NPT and RMP entry.
I will move the APIC backing page setup to per-CPU setup (x2apic_savic_setup()) and
use that pointer to do the check.


- Neeraj