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Date:   Tue, 8 Jun 2021 10:59:41 -0500
From:   Venu Busireddy <venu.busireddy@oracle.com>
To:     Brijesh Singh <brijesh.singh@amd.com>
Cc:     x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
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        David Rientjes <rientjes@google.com>, tony.luck@intel.com,
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Subject: Re: [PATCH Part1 RFC v3 02/22] x86/sev: Define the Linux specific
 guest termination reasons
Message-ID: <YL+T7X/417sQAUUA@dt>
References: <20210602140416.23573-1-brijesh.singh@amd.com>
 <20210602140416.23573-3-brijesh.singh@amd.com>
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On 2021-06-02 09:03:56 -0500, Brijesh Singh wrote:
> GHCB specification defines the reason code for reason set 0. The reason
> codes defined in the set 0 do not cover all possible causes for a guest
> to request termination.
> 
> The reason set 1 to 255 is reserved for the vendor-specific codes.
> Reseve the reason set 1 for the Linux guest. Define an error codes for
> reason set 1.
> 
> While at it, change the sev_es_terminate() to accept the reason set
> parameter.
> 
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> ---
>  arch/x86/boot/compressed/sev.c    | 6 +++---
>  arch/x86/include/asm/sev-common.h | 5 +++++
>  arch/x86/kernel/sev-shared.c      | 6 +++---
>  arch/x86/kernel/sev.c             | 4 ++--
>  4 files changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c
> index 28bcf04c022e..87621f4e4703 100644
> --- a/arch/x86/boot/compressed/sev.c
> +++ b/arch/x86/boot/compressed/sev.c
> @@ -122,7 +122,7 @@ static enum es_result vc_read_mem(struct es_em_ctxt *ctxt,
>  static bool early_setup_sev_es(void)
>  {
>  	if (!sev_es_negotiate_protocol())
> -		sev_es_terminate(GHCB_SEV_ES_PROT_UNSUPPORTED);
> +		sev_es_terminate(0, GHCB_SEV_ES_PROT_UNSUPPORTED);
>  
>  	if (set_page_decrypted((unsigned long)&boot_ghcb_page))
>  		return false;
> @@ -175,7 +175,7 @@ void do_boot_stage2_vc(struct pt_regs *regs, unsigned long exit_code)
>  	enum es_result result;
>  
>  	if (!boot_ghcb && !early_setup_sev_es())
> -		sev_es_terminate(GHCB_SEV_ES_GEN_REQ);
> +		sev_es_terminate(0, GHCB_SEV_ES_GEN_REQ);
>  
>  	vc_ghcb_invalidate(boot_ghcb);
>  	result = vc_init_em_ctxt(&ctxt, regs, exit_code);
> @@ -202,5 +202,5 @@ void do_boot_stage2_vc(struct pt_regs *regs, unsigned long exit_code)
>  	if (result == ES_OK)
>  		vc_finish_insn(&ctxt);
>  	else if (result != ES_RETRY)
> -		sev_es_terminate(GHCB_SEV_ES_GEN_REQ);
> +		sev_es_terminate(0, GHCB_SEV_ES_GEN_REQ);
>  }
> diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
> index 11b7d9cea775..f1e2aacb0d61 100644
> --- a/arch/x86/include/asm/sev-common.h
> +++ b/arch/x86/include/asm/sev-common.h
> @@ -59,4 +59,9 @@
>  
>  #define GHCB_RESP_CODE(v)		((v) & GHCB_MSR_INFO_MASK)
>  
> +/* Linux specific reason codes (used with reason set 1) */
> +#define GHCB_TERM_REGISTER		0	/* GHCB GPA registration failure */
> +#define GHCB_TERM_PSC			1	/* Page State Change failure */
> +#define GHCB_TERM_PVALIDATE		2	/* Pvalidate failure */
> +
>  #endif
> diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c
> index 14198075ff8b..de0e7e6c52b8 100644
> --- a/arch/x86/kernel/sev-shared.c
> +++ b/arch/x86/kernel/sev-shared.c
> @@ -24,7 +24,7 @@ static bool __init sev_es_check_cpu_features(void)
>  	return true;
>  }
>  
> -static void __noreturn sev_es_terminate(unsigned int reason)
> +static void __noreturn sev_es_terminate(unsigned int set, unsigned int reason)
>  {
>  	u64 val = GHCB_MSR_TERM_REQ;
>  
> @@ -32,7 +32,7 @@ static void __noreturn sev_es_terminate(unsigned int reason)
>  	 * Tell the hypervisor what went wrong - only reason-set 0 is
>  	 * currently supported.
>  	 */

Since reason set 0 is not the only set supported anymore, maybe the part
about reason set 0 should be removed from the above comment?

Venu

> -	val |= GHCB_SEV_TERM_REASON(0, reason);
> +	val |= GHCB_SEV_TERM_REASON(set, reason);
>  
>  	/* Request Guest Termination from Hypvervisor */
>  	sev_es_wr_ghcb_msr(val);
> @@ -207,7 +207,7 @@ void __init do_vc_no_ghcb(struct pt_regs *regs, unsigned long exit_code)
>  
>  fail:
>  	/* Terminate the guest */
> -	sev_es_terminate(GHCB_SEV_ES_GEN_REQ);
> +	sev_es_terminate(0, GHCB_SEV_ES_GEN_REQ);
>  }
>  
>  static enum es_result vc_insn_string_read(struct es_em_ctxt *ctxt,
> diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
> index 460717e3f72d..77a754365ba9 100644
> --- a/arch/x86/kernel/sev.c
> +++ b/arch/x86/kernel/sev.c
> @@ -1383,7 +1383,7 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication)
>  		show_regs(regs);
>  
>  		/* Ask hypervisor to sev_es_terminate */
> -		sev_es_terminate(GHCB_SEV_ES_GEN_REQ);
> +		sev_es_terminate(0, GHCB_SEV_ES_GEN_REQ);
>  
>  		/* If that fails and we get here - just panic */
>  		panic("Returned from Terminate-Request to Hypervisor\n");
> @@ -1416,7 +1416,7 @@ bool __init handle_vc_boot_ghcb(struct pt_regs *regs)
>  
>  	/* Do initial setup or terminate the guest */
>  	if (unlikely(boot_ghcb == NULL && !sev_es_setup_ghcb()))
> -		sev_es_terminate(GHCB_SEV_ES_GEN_REQ);
> +		sev_es_terminate(0, GHCB_SEV_ES_GEN_REQ);
>  
>  	vc_ghcb_invalidate(boot_ghcb);
>  
> -- 
> 2.17.1
>