linux-kernel - Re: [PATCH v3 01/17] x86/apic: Add new driver for Secure AVIC

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Message-ID: <874iz5wk9v.ffs@tglx>
Date: Thu, 03 Apr 2025 13:34:52 +0200
From: Thomas Gleixner <tglx@...utronix.de>
To: Neeraj Upadhyay <Neeraj.Upadhyay@....com>, linux-kernel@...r.kernel.org
Cc: bp@...en8.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, kirill.shutemov@...ux.intel.com,
 huibo.wang@....com, naveen.rao@....com, francescolavra.fl@...il.com
Subject: Re: [PATCH v3 01/17] x86/apic: Add new driver for Secure AVIC

On Tue, Apr 01 2025 at 17:06, Neeraj Upadhyay wrote:
> +static void __send_ipi_mask(const struct cpumask *mask, int vector, bool excl_self)
> +{
> +	unsigned long query_cpu;
> +	unsigned long this_cpu;
> +	unsigned long flags;

Just coalesce them into a single line: 'unsigned long a, b;'

> +	/* x2apic MSRs are special and need a special fence: */
> +	weak_wrmsr_fence();
> +
> +	local_irq_save(flags);

        guard(irqsave)();

> +	this_cpu = smp_processor_id();
> +	for_each_cpu(query_cpu, mask) {
> +		if (excl_self && this_cpu == query_cpu)
> +			continue;
> +		__x2apic_send_IPI_dest(per_cpu(x86_cpu_to_apicid, query_cpu),
> +				       vector, APIC_DEST_PHYSICAL);
> +	}
> +	local_irq_restore(flags);
> +}

> +static int x2apic_savic_probe(void)
> +{
> +	if (!cc_platform_has(CC_ATTR_SNP_SECURE_AVIC))
> +		return 0;
> +
> +	if (!x2apic_mode) {
> +		pr_err("Secure AVIC enabled in non x2APIC mode\n");
> +		snp_abort();

Why does this return 1?

> +	}
> +
> +	return 1;
> +}