Re: [PATCH v8 27/40] x86/boot: Add Confidential Computing type to setup_data

Venu Busireddy
2022-01-06T22:49:37Z

On 2021-12-10 09:43:19 -0600, Brijesh Singh wrote:
> While launching the encrypted guests, the hypervisor may need to provide
> some additional information during the guest boot. When booting under the
> EFI based BIOS, the EFI configuration table contains an entry for the
> confidential computing blob that contains the required information.
>
> To support booting encrypted guests on non-EFI VM, the hypervisor needs to
> pass this additional information to the kernel with a different method.
>
> For this purpose, introduce SETUP_CC_BLOB type in setup_data to hold the
> physical address of the confidential computing blob location. The boot
> loader or hypervisor may choose to use this method instead of EFI
> configuration table. The CC blob location scanning should give preference
> to setup_data data over the EFI configuration table.
>
> In AMD SEV-SNP, the CC blob contains the address of the secrets and CPUID
> pages. The secrets page includes information such as a VM to PSP
> communication key and CPUID page contains PSP filtered CPUID values.
> Define the AMD SEV confidential computing blob structure.
>
> While at it, define the EFI GUID for the confidential computing blob.
>
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>

Reviewed-by: Venu Busireddy <venu.busireddy@oracle.com>

> ---
> arch/x86/include/asm/sev.h | 12 ++++++++++++
> arch/x86/include/uapi/asm/bootparam.h | 1 +
> include/linux/efi.h | 1 +
> 3 files changed, 14 insertions(+)
>
> diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
> index f7cbd5164136..f42fbe3c332f 100644
> --- a/arch/x86/include/asm/sev.h
> +++ b/arch/x86/include/asm/sev.h
> @@ -44,6 +44,18 @@ struct es_em_ctxt {
>
> void do_vc_no_ghcb(struct pt_regs *regs, unsigned long exit_code);
>
> +/* AMD SEV Confidential computing blob structure */
> +#define CC_BLOB_SEV_HDR_MAGIC 0x45444d41
> +struct cc_blob_sev_info {
> + u32 magic;
> + u16 version;
> + u16 reserved;
> + u64 secrets_phys;
> + u32 secrets_len;
> + u64 cpuid_phys;
> + u32 cpuid_len;
> +};
> +
> static inline u64 lower_bits(u64 val, unsigned int bits)
> {
> u64 mask = (1ULL << bits) - 1;
> diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h
> index b25d3f82c2f3..1ac5acca72ce 100644
> --- a/arch/x86/include/uapi/asm/bootparam.h
> +++ b/arch/x86/include/uapi/asm/bootparam.h
> @@ -10,6 +10,7 @@
> #define SETUP_EFI 4
> #define SETUP_APPLE_PROPERTIES 5
> #define SETUP_JAILHOUSE 6
> +#define SETUP_CC_BLOB 7
>
> #define SETUP_INDIRECT (1<<31)
>
> diff --git a/include/linux/efi.h b/include/linux/efi.h
> index dbd39b20e034..a022aed7adb3 100644
> --- a/include/linux/efi.h
> +++ b/include/linux/efi.h
> @@ -344,6 +344,7 @@ void efi_native_runtime_setup(void);
> #define EFI_CERT_SHA256_GUID EFI_GUID(0xc1c41626, 0x504c, 0x4092, 0xac, 0xa9, 0x41, 0xf9, 0x36, 0x93, 0x43, 0x28)
> #define EFI_CERT_X509_GUID EFI_GUID(0xa5c059a1, 0x94e4, 0x4aa7, 0x87, 0xb5, 0xab, 0x15, 0x5c, 0x2b, 0xf0, 0x72)
> #define EFI_CERT_X509_SHA256_GUID EFI_GUID(0x3bd2a492, 0x96c0, 0x4079, 0xb4, 0x20, 0xfc, 0xf9, 0x8e, 0xf1, 0x03, 0xed)
> +#define EFI_CC_BLOB_GUID EFI_GUID(0x067b1f5f, 0xcf26, 0x44c5, 0x85, 0x54, 0x93, 0xd7, 0x77, 0x91, 0x2d, 0x42)
>
> /*
> * This GUID is used to pass to the kernel proper the struct screen_info
> --
> 2.25.1
>