Re: [PATCH Part1 RFC v3 02/22] x86/sev: Define the Linux specific guest termination reasons

Venu Busireddy
2021-06-08T16:01:22Z

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
>