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Date:   Thu, 21 Oct 2021 18:22:26 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     Tianyu Lan <ltykernel@gmail.com>
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Subject: Re: [PATCH V8 5/9] x86/sev-es: Expose sev_es_ghcb_hv_call() to call
 ghcb hv call out of sev code
Message-ID: <YXGTwppQ8syUyJ72@zn.tnic>
References: <20211021154110.3734294-1-ltykernel@gmail.com>
 <20211021154110.3734294-6-ltykernel@gmail.com>
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On Thu, Oct 21, 2021 at 11:41:05AM -0400, Tianyu Lan wrote:
> diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c
> index ea9abd69237e..368ed36971e3 100644
> --- a/arch/x86/kernel/sev-shared.c
> +++ b/arch/x86/kernel/sev-shared.c
> @@ -124,10 +124,9 @@ static enum es_result verify_exception_info(struct ghcb *ghcb, struct es_em_ctxt
>  	return ES_VMM_ERROR;
>  }
>  
> -static enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb,
> -					  struct es_em_ctxt *ctxt,
> -					  u64 exit_code, u64 exit_info_1,
> -					  u64 exit_info_2)
> +enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb, bool set_ghcb_msr,
> +				   struct es_em_ctxt *ctxt, u64 exit_code,
> +				   u64 exit_info_1, u64 exit_info_2)
>  {
>  	/* Fill in protocol and format specifiers */
>  	ghcb->protocol_version = GHCB_PROTOCOL_MAX;
> @@ -137,7 +136,15 @@ static enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb,
>  	ghcb_set_sw_exit_info_1(ghcb, exit_info_1);
>  	ghcb_set_sw_exit_info_2(ghcb, exit_info_2);
>  
> -	sev_es_wr_ghcb_msr(__pa(ghcb));
> +	/*
> +	 * Hyper-V unenlightened guests use a paravisor for communicating and
> +	 * GHCB pages are being allocated and set up by that paravisor. Linux
> +	 * should not change ghcb page pa in such case and so add set_ghcb_msr

"... not change the GHCB page's physical address."

Remove the "so add... " rest.

Otherwise, LGTM.

Do you want me to take it through the tip tree?

Thx.

-- 
Regards/Gruss,
    Boris.

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