linux-kernel - Re: [PATCHv6 17/30] x86/tdx: Port I/O: add runtime hypercalls

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Date:   Thu, 17 Mar 2022 13:25:13 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...el.com,
        luto@...nel.org, peterz@...radead.org
Cc:     sathyanarayanan.kuppuswamy@...ux.intel.com, aarcange@...hat.com,
        ak@...ux.intel.com, dan.j.williams@...el.com, david@...hat.com,
        hpa@...or.com, jgross@...e.com, jmattson@...gle.com,
        joro@...tes.org, jpoimboe@...hat.com, knsathya@...nel.org,
        pbonzini@...hat.com, sdeep@...are.com, seanjc@...gle.com,
        tony.luck@...el.com, vkuznets@...hat.com, wanpengli@...cent.com,
        thomas.lendacky@....com, brijesh.singh@....com, x86@...nel.org,
        linux-kernel@...r.kernel.org,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>
Subject: Re: [PATCHv6 17/30] x86/tdx: Port I/O: add runtime hypercalls

On Wed, Mar 16 2022 at 05:08, Kirill A. Shutemov wrote:
> +static bool handle_in(struct pt_regs *regs, int size, int port)
> +{
> +	struct tdx_hypercall_args args = {
> +		.r10 = TDX_HYPERCALL_STANDARD,
> +		.r11 = hcall_func(EXIT_REASON_IO_INSTRUCTION),
> +		.r12 = size,
> +		.r13 = PORT_READ,
> +		.r14 = port,
> +	};
> +	bool success;
> +	u64 mask = GENMASK(BITS_PER_BYTE * size, 0);

Reverse fir tree ordering please:

	u64 mask = GENMASK(BITS_PER_BYTE * size, 0);
	bool success;

> +/*
> + * Emulate I/O using hypercall.
> + *
> + * Assumes the IO instruction was using ax, which is enforced
> + * by the standard io.h macros.
> + *
> + * Return True on success or False on failure.
> + */
> +static bool handle_io(struct pt_regs *regs, u32 exit_qual)
> +{
> +	bool in;
> +	int size, port;

Ditto.

Other than that:

Reviewed-by: Thomas Gleixner <tglx@...utronix.de>