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From: Thomas Gleixner <tglx@linutronix.de>
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To: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com>, linux-kernel@vger.kernel.org
Cc: bp@alien8.de, mingo@redhat.com, dave.hansen@linux.intel.com,
 Thomas.Lendacky@amd.com, nikunj@amd.com, Santosh.Shukla@amd.com,
 Vasant.Hegde@amd.com, Suravee.Suthikulpanit@amd.com, David.Kaplan@amd.com,
 x86@kernel.org, hpa@zytor.com, peterz@infradead.org, seanjc@google.com,
 pbonzini@redhat.com, kvm@vger.kernel.org, kirill.shutemov@linux.intel.com,
 huibo.wang@amd.com, naveen.rao@amd.com
Subject: Re: [RFC v2 13/17] x86/apic: Handle EOI writes for SAVIC guests
In-Reply-To: <20250226090525.231882-14-Neeraj.Upadhyay@amd.com>
References: <20250226090525.231882-1-Neeraj.Upadhyay@amd.com>
 <20250226090525.231882-14-Neeraj.Upadhyay@amd.com>
Date: Fri, 21 Mar 2025 16:41:45 +0100
Message-ID: <87cyea2xxi.ffs@tglx>
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On Wed, Feb 26 2025 at 14:35, Neeraj Upadhyay wrote:
> +static int find_highest_isr(void *backing_page)
> +{
> +	int vec_per_reg = 32;
> +	int max_vec = 256;
> +	u32 reg;
> +	int vec;
> +
> +	for (vec = max_vec - 32; vec >= 0; vec -= vec_per_reg) {
> +		reg = get_reg(backing_page, APIC_ISR + REG_POS(vec));
> +		if (reg)
> +			return __fls(reg) + vec;
> +	}
> +
> +	return -1;

Congrats. You managed to re-implement find_last_bit() in the most
incomprehesible way.

Thanks,

        tglx