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Message-ID: <878ruuxkcc.ffs@tglx>
Date: Wed, 02 Feb 2022 00:01:23 +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,
x86@...nel.org, linux-kernel@...r.kernel.org,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: Re: [PATCHv2 13/29] x86/tdx: Add port I/O emulation
On Mon, Jan 24 2022 at 18:01, Kirill A. Shutemov wrote:
> static bool intel_cc_platform_has(enum cc_attr attr)
> {
> + if (attr == CC_ATTR_GUEST_UNROLL_STRING_IO)
> + return true;
> +
switch (attr) perhaps as there are more coming, right?
> return false;
> }
> +/*
> + * 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 tdx_handle_io(struct pt_regs *regs, u32 exit_qual)
> +{
> + struct tdx_hypercall_output out;
> + int size, port, ret;
> + u64 mask;
> + bool in;
> +
> + if (VE_IS_IO_STRING(exit_qual))
> + return false;
> +
> + in = VE_IS_IO_IN(exit_qual);
> + size = VE_GET_IO_SIZE(exit_qual);
> + port = VE_GET_PORT_NUM(exit_qual);
> + mask = GENMASK(BITS_PER_BYTE * size, 0);
> +
> + /*
> + * Emulate the I/O read/write via hypercall. More info about
> + * ABI can be found in TDX Guest-Host-Communication Interface
> + * (GHCI) sec titled "TDG.VP.VMCALL<Instruction.IO>".
> + */
> + ret = _tdx_hypercall(EXIT_REASON_IO_INSTRUCTION, size, !in, port,
> + in ? 0 : regs->ax, &out);
> + if (!in)
> + return !ret;
> +
> + regs->ax &= ~mask;
> + regs->ax |= ret ? UINT_MAX : out.r11 & mask;
> +
> + return !ret;
> +}
> +
> bool tdx_get_ve_info(struct ve_info *ve)
> {
> struct tdx_module_output out;
> @@ -333,6 +378,9 @@ static bool tdx_virt_exception_kernel(struct pt_regs *regs, struct ve_info *ve)
> if (!ret)
> pr_warn_once("MMIO failed\n");
> break;
> + case EXIT_REASON_IO_INSTRUCTION:
> + ret = tdx_handle_io(regs, ve->exit_qual);
return ...
Other than that LGTM.
Thanks,
tglx
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