linux-kernel - Re: [PATCH v6 42/76] x86/sev-es: Setup early #VC handler

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Date:   Mon, 31 Aug 2020 11:45:41 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Joerg Roedel <joro@...tes.org>
Cc:     x86@...nel.org, Joerg Roedel <jroedel@...e.de>, hpa@...or.com,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Jiri Slaby <jslaby@...e.cz>,
        Dan Williams <dan.j.williams@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Juergen Gross <jgross@...e.com>,
        Kees Cook <keescook@...omium.org>,
        David Rientjes <rientjes@...gle.com>,
        Cfir Cohen <cfir@...gle.com>,
        Erdem Aktas <erdemaktas@...gle.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Mike Stunes <mstunes@...are.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Martin Radev <martin.b.radev@...il.com>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH v6 42/76] x86/sev-es: Setup early #VC handler

On Mon, Aug 24, 2020 at 10:54:37AM +0200, Joerg Roedel wrote:
> +#ifdef CONFIG_AMD_MEM_ENCRYPT
> +static void set_early_idt_handler(gate_desc *idt, int n, void *handler)
> +{
> +	struct idt_data data;
> +	gate_desc desc;
> +
> +	init_idt_data(&data, n, handler);
> +	idt_init_desc(&desc, &data);
> +	native_write_idt_entry(idt, n, &desc);
> +}
> +#endif
> +
> +static struct desc_ptr early_idt_descr __initdata = {
> +	.size		= IDT_TABLE_SIZE - 1,
> +	.address	= 0 /* Needs physical address of idt_table - initialized at runtime. */,
> +};
> +
> +void __init early_idt_setup(unsigned long physbase)
> +{
> +	void __maybe_unused *handler;
> +	gate_desc *idt;
> +
> +	idt = fixup_pointer(idt_table, physbase);
> +
> +#ifdef CONFIG_AMD_MEM_ENCRYPT
> +	/* VMM Communication Exception */
> +	handler = fixup_pointer(vc_no_ghcb, physbase);
> +	set_early_idt_handler(idt, X86_TRAP_VC, handler);

This function is used only once AFAICT - you might just as well add its
three-lined body here and save yourself the function definition and
ifdeffery above...

> +#endif
> +
> +	/* Initialize IDT descriptor and load IDT */
> +	early_idt_descr.address = (unsigned long)idt;
> +	native_load_idt(&early_idt_descr);
> +}
> -- 
> 2.28.0
> 

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette