RE: [EXTERNAL] [RFC PATCH V5 09/15] x86/hyperv: Add smp support for sev-snp guest

[Saurabh Singh Sengar <ssengar@microsoft.com>]

> -----Original Message-----
> From: Tianyu Lan <ltykernel@gmail.com>
> Sent: Monday, May 1, 2023 2:27 PM
> To: luto@kernel.org; tglx@linutronix.de; mingo@redhat.com; bp@alien8.de;
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> linux-hyperv@vger.kernel.org; linux-arch@vger.kernel.org
> Subject: [EXTERNAL] [RFC PATCH V5 09/15] x86/hyperv: Add smp support for
> sev-snp guest
> 
> From: Tianyu Lan <tiala@microsoft.com>
> 
> The wakeup_secondary_cpu callback was populated with wakeup_
> cpu_via_vmgexit() which doesn't work for Hyper-V and Hyper-V requires to
> call Hyper-V specific hvcall to start APs. So override it with Hyper-V specific
> hook to start AP sev_es_save_area data structure.
> 
> Signed-off-by: Tianyu Lan <tiala@microsoft.com>
> ---
> Change sicne RFC v3:
>        * Replace struct sev_es_save_area with struct
>          vmcb_save_area
>        * Move code from mshyperv.c to ivm.c
> 
> Change since RFC v2:
>        * Add helper function to initialize segment
>        * Fix some coding style
> ---
>  arch/x86/hyperv/ivm.c             | 89 +++++++++++++++++++++++++++++++
>  arch/x86/include/asm/mshyperv.h   | 18 +++++++
>  arch/x86/include/asm/sev.h        | 13 +++++
>  arch/x86/include/asm/svm.h        | 15 +++++-
>  arch/x86/kernel/cpu/mshyperv.c    | 13 ++++-
>  arch/x86/kernel/sev.c             |  4 +-
>  include/asm-generic/hyperv-tlfs.h | 19 +++++++
>  7 files changed, 166 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c index
> 522eab55c0dd..0ef46f1874e6 100644
> --- a/arch/x86/hyperv/ivm.c
> +++ b/arch/x86/hyperv/ivm.c
> @@ -22,11 +22,15 @@
>  #include <asm/sev.h>
>  #include <asm/realmode.h>
>  #include <asm/e820/api.h>
> +#include <asm/desc.h>
> 
>  #ifdef CONFIG_AMD_MEM_ENCRYPT
> 
>  #define GHCB_USAGE_HYPERV_CALL	1
> 
> +static u8 ap_start_input_arg[PAGE_SIZE] __bss_decrypted
> +__aligned(PAGE_SIZE); static u8 ap_start_stack[PAGE_SIZE]
> +__aligned(PAGE_SIZE);
> +
>  union hv_ghcb {
>  	struct ghcb ghcb;
>  	struct {
> @@ -442,6 +446,91 @@ __init void hv_sev_init_mem_and_cpu(void)
>  	}
>  }
> 
> +#define hv_populate_vmcb_seg(seg, gdtr_base)			\
> +do {								\
> +	if (seg.selector) {					\
> +		seg.base = 0;					\
> +		seg.limit = HV_AP_SEGMENT_LIMIT;		\
> +		seg.attrib = *(u16 *)(gdtr_base + seg.selector + 5);	\

<snip>

> generic/hyperv-tlfs.h b/include/asm-generic/hyperv-tlfs.h
> index f4e4cc4f965f..959b075591b2 100644
> --- a/include/asm-generic/hyperv-tlfs.h
> +++ b/include/asm-generic/hyperv-tlfs.h
> @@ -149,6 +149,7 @@ union hv_reference_tsc_msr {
>  #define HVCALL_ENABLE_VP_VTL			0x000f
>  #define HVCALL_NOTIFY_LONG_SPIN_WAIT		0x0008
>  #define HVCALL_SEND_IPI				0x000b
> +#define HVCALL_ENABLE_VP_VTL			0x000f

HVCALL_ENABLE_VP_VTL is already defined.

>  #define HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX	0x0013
>  #define HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX	0x0014
>  #define HVCALL_SEND_IPI_EX			0x0015
> @@ -168,6 +169,7 @@ union hv_reference_tsc_msr {
>  #define HVCALL_RETARGET_INTERRUPT		0x007e
>  #define HVCALL_START_VP				0x0099
>  #define HVCALL_GET_VP_ID_FROM_APIC_ID		0x009a
> +#define HVCALL_START_VIRTUAL_PROCESSOR		0x0099

We already have HVCALL_START_VP no need of defining HVCALL_START_VIRTUAL_PROCESSOR.
- Saurabh

>  #define HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_SPACE 0x00af  #define
> HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_LIST 0x00b0  #define
> HVCALL_MODIFY_SPARSE_GPA_PAGE_HOST_VISIBILITY 0x00db @@ -223,6
> +225,7 @@ enum HV_GENERIC_SET_FORMAT {
>  #define HV_STATUS_INVALID_PORT_ID		17
>  #define HV_STATUS_INVALID_CONNECTION_ID		18
>  #define HV_STATUS_INSUFFICIENT_BUFFERS		19
> +#define HV_STATUS_TIME_OUT                      120
>  #define HV_STATUS_VTL_ALREADY_ENABLED		134
> 
>  /*
> @@ -783,6 +786,22 @@ struct hv_input_unmap_device_interrupt {
>  	struct hv_interrupt_entry interrupt_entry;  } __packed;
> 
> +struct hv_enable_vp_vtl_input {
> +	u64 partitionid;
> +	u32 vpindex;
> +	u8 targetvtl;
> +	u8 padding[3];
> +	u8 context[0xe0];
> +} __packed;
> +
> +struct hv_start_virtual_processor_input {
> +	u64 partitionid;
> +	u32 vpindex;
> +	u8 targetvtl;
> +	u8 padding[3];
> +	u8 context[0xe0];
> +} __packed;
> +
>  #define HV_SOURCE_SHADOW_NONE               0x0
>  #define HV_SOURCE_SHADOW_BRIDGE_BUS_RANGE   0x1
> 
> --
> 2.25.1