linux-kernel - Re: [PATCH v5 10/12] x86/tdx: Add MSR support for TDX guest

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Message-ID: <YSUkaUQtUpqAXCVd@zn.tnic>
Date:   Tue, 24 Aug 2021 18:55:05 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Peter H Anvin <hpa@...or.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 10/12] x86/tdx: Add MSR support for TDX guest

On Wed, Aug 04, 2021 at 11:13:27AM -0700, Kuppuswamy Sathyanarayanan wrote:
>  int tdg_handle_virtualization_exception(struct pt_regs *regs,
>  					struct ve_info *ve)
>  {
> +	unsigned long val;
> +	int ret = 0;
> +
>  	switch (ve->exit_reason) {
>  	case EXIT_REASON_HLT:
>  		tdg_halt();
>  		break;
> +	case EXIT_REASON_MSR_READ:
> +		val = tdg_read_msr_safe(regs->cx, (unsigned int *)&ret);
> +		if (!ret) {
> +			regs->ax = val & UINT_MAX;

			regs->ax = (u32)val;

> +			regs->dx = val >> 32;
> +		}
> +		break;
> +	case EXIT_REASON_MSR_WRITE:
> +		ret = tdg_write_msr_safe(regs->cx, regs->ax, regs->dx);
> +		break;
>  	default:
>  		pr_warn("Unexpected #VE: %lld\n", ve->exit_reason);
>  		return -EFAULT;
>  	}
>  
>  	/* After successful #VE handling, move the IP */
> -	regs->ip += ve->instr_len;
> +	if (!ret)
> +		regs->ip += ve->instr_len;
>  
> -	return 0;
> +	return ret;
>  }
>  
>  void __init tdx_early_init(void)
> -- 

-- 
Regards/Gruss,
    Boris.

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