On Fri, Apr 30, 2021 at 07:16:01AM -0500, Brijesh Singh wrote:
> An SNP-active guest will use the page state change NAE VMGEXIT defined in
> the GHCB specification to ask the hypervisor to make the guest page
> private or shared in the RMP table. In addition to the private/shared,
> the guest can also ask the hypervisor to split or combine multiple 4K
> validated pages as a single 2M page or vice versa.
>
> See GHCB specification section Page State Change for additional
> information.
>
> Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
> ---
> arch/x86/include/asm/sev-common.h | 46 +++++++++++++++++++++++++++++++
> arch/x86/include/uapi/asm/svm.h | 2 ++
> 2 files changed, 48 insertions(+)
>
> diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
> index 8142e247d8da..07b8612bf182 100644
> --- a/arch/x86/include/asm/sev-common.h
> +++ b/arch/x86/include/asm/sev-common.h
> @@ -67,6 +67,52 @@
> #define GHCB_HV_FEATURES_SNP_RESTRICTED_INJECTION_TIMER \
> (BIT_ULL(3) | GHCB_HV_FEATURES_SNP_RESTRICTED_INJECTION)
>
> +/* SNP Page State Change */
> +#define GHCB_MSR_PSC_REQ 0x014
> +#define SNP_PAGE_STATE_PRIVATE 1
> +#define SNP_PAGE_STATE_SHARED 2
> +#define SNP_PAGE_STATE_PSMASH 3
> +#define SNP_PAGE_STATE_UNSMASH 4
> +#define GHCB_MSR_PSC_GFN_POS 12
> +#define GHCB_MSR_PSC_GFN_MASK 0xffffffffffULL
Why don't you use GENMASK_ULL() as I suggested? All those "f"s are
harder to count than seeing the start and end of a mask.
> +#define GHCB_MSR_PSC_OP_POS 52
Also, having defines for 12 and 52 doesn't make it more readable,
frankly.
When I see GENMASK_ULL(51, 12) it is kinda clear what it is. With the
defines, I have to go chase every define and replace it with the number
mentally.
> +#define GHCB_MSR_PSC_OP_MASK 0xf
> +#define GHCB_MSR_PSC_REQ_GFN(gfn, op) \
> + (((unsigned long)((op) & GHCB_MSR_PSC_OP_MASK) << GHCB_MSR_PSC_OP_POS) | \
> + (((gfn) << GHCB_MSR_PSC_GFN_POS) & GHCB_MSR_PSC_GFN_MASK) | GHCB_MSR_PSC_REQ)
> +
> +#define GHCB_MSR_PSC_RESP 0x015
> +#define GHCB_MSR_PSC_ERROR_POS 32
> +#define GHCB_MSR_PSC_ERROR_MASK 0xffffffffULL
> +#define GHCB_MSR_PSC_RSVD_POS 12
> +#define GHCB_MSR_PSC_RSVD_MASK 0xfffffULL
> +#define GHCB_MSR_PSC_RESP_VAL(val) ((val) >> GHCB_MSR_PSC_ERROR_POS)
> +
> +/* SNP Page State Change NAE event */
> +#define VMGEXIT_PSC_MAX_ENTRY 253
> +#define VMGEXIT_PSC_INVALID_HEADER 0x100000001
> +#define VMGEXIT_PSC_INVALID_ENTRY 0x100000002
> +#define VMGEXIT_PSC_FIRMWARE_ERROR(x) ((x & 0xffffffffULL) | 0x200000000)
> +
> +struct __packed snp_page_state_header {
> + u16 cur_entry;
> + u16 end_entry;
> + u32 reserved;
> +};
> +
> +struct __packed snp_page_state_entry {
> + u64 cur_page:12;
> + u64 gfn:40;
> + u64 operation:4;
> + u64 pagesize:1;
> + u64 reserved:7;
Please write it like this:
u64 cur_page : 12,
gfn : 40,
...
to show that all those fields are part of the same u64.
struct perf_event_attr in include/uapi/linux/perf_event.h is a good
example.
> +};
> +
> +struct __packed snp_page_state_change {
> + struct snp_page_state_header header;
> + struct snp_page_state_entry entry[VMGEXIT_PSC_MAX_ENTRY];
> +};
> +
> #define GHCB_MSR_TERM_REQ 0x100
> #define GHCB_MSR_TERM_REASON_SET_POS 12
> #define GHCB_MSR_TERM_REASON_SET_MASK 0xf
> diff --git a/arch/x86/include/uapi/asm/svm.h b/arch/x86/include/uapi/asm/svm.h
> index 7fbc311e2de1..f7bf12cad58c 100644
> --- a/arch/x86/include/uapi/asm/svm.h
> +++ b/arch/x86/include/uapi/asm/svm.h
> @@ -108,6 +108,7 @@
> #define SVM_VMGEXIT_AP_JUMP_TABLE 0x80000005
> #define SVM_VMGEXIT_SET_AP_JUMP_TABLE 0
> #define SVM_VMGEXIT_GET_AP_JUMP_TABLE 1
> +#define SVM_VMGEXIT_SNP_PAGE_STATE_CHANGE 0x80000010
SVM_VMGEXIT_SNP_PSC
> #define SVM_VMGEXIT_HYPERVISOR_FEATURES 0x8000fffd
> #define SVM_VMGEXIT_UNSUPPORTED_EVENT 0x8000ffff
>
> @@ -216,6 +217,7 @@
> { SVM_VMGEXIT_NMI_COMPLETE, "vmgexit_nmi_complete" }, \
> { SVM_VMGEXIT_AP_HLT_LOOP, "vmgexit_ap_hlt_loop" }, \
> { SVM_VMGEXIT_AP_JUMP_TABLE, "vmgexit_ap_jump_table" }, \
> + { SVM_VMGEXIT_SNP_PAGE_STATE_CHANGE, "vmgexit_page_state_change" }, \
Ditto.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
