Re: [RFC PATCH V3 00/16] x86/hyperv/sev: Add AMD sev-snp enlightened guest support on hyperv

[Zhi Wang <zhi.wang.linux@gmail.com>]

On Sat, 21 Jan 2023 21:45:50 -0500
Tianyu Lan <ltykernel@gmail.com> wrote:

1) I am thinking if it is a good time to organize a common code path for
enlightened VM on hyper-v.

Wouldn't it be better to have a common flag for enlightened VM? 
Like bool hv_isolation_type_enlightened()

Many of the decryption of the post msg page... are also required
in the enlightened TDX guest, they are not AMD-specific. 

Then in the "TDX guest on hyper-V" patch set, Dexuan can save some LOCs instead
of ending up with if (hv_isolation_type_en_snp() ||
hv_isolation_type_en_tdx())...

2) It seems the AMD SEV-SNP enlightened guest on hyper-V is implemented as
CC_VENDOR_AMD, while TDX enlightened guest is still implemented as
CC_VENDOR_HYPERV. I am curious about the reason.

> From: Tianyu Lan <tiala@microsoft.com>
> 
> This patchset is to add AMD sev-snp enlightened guest
> support on hyperv. Hyperv uses Linux direct boot mode
> to boot up Linux kernel and so it needs to pvalidate
> system memory by itself.
> 
> In hyperv case, there is no boot loader and so cc blob
> is prepared by hypervisor. In this series, hypervisor
> set the cc blob address directly into boot parameter
> of Linux kernel. If the magic number on cc blob address
> is valid, kernel will read cc blob.
> 
> Shared memory between guests and hypervisor should be
> decrypted and zero memory after decrypt memory. The data
> in the target address. It maybe smearedto avoid smearing
> data.
> 
> Introduce #HV exception support in AMD sev snp code and
> #HV handler.
> 
> Change since v2:
>        - Remove validate kernel memory code at boot stage
>        - Split #HV page patch into two parts
>        - Remove HV-APIC change due to enable x2apic from
>        	 host side
>        - Rework vmbus code to handle error of decrypt page
>        - Spilt memory and cpu initialization patch. 
> 
> Change since v1:
>        - Remove boot param changes for cc blob address and
>        use setup head to pass cc blob info
>        - Remove unnessary WARN and BUG check
>        - Add system vector table map in the #HV exception
>        - Fix interrupt exit issue when use #HV exception
> 
> Ashish Kalra (2):
>   x86/sev: optimize system vector processing invoked from #HV exception
>   x86/sev: Fix interrupt exit code paths from #HV exception
> 
> Tianyu Lan (14):
>   x86/hyperv: Add sev-snp enlightened guest specific config
>   x86/hyperv: Decrypt hv vp assist page in sev-snp enlightened guest
>   x86/hyperv: Set Virtual Trust Level in vmbus init message
>   x86/hyperv: Use vmmcall to implement Hyper-V hypercall in sev-snp
>     enlightened guest
>   clocksource/drivers/hyper-v: decrypt hyperv tsc page in sev-snp
>     enlightened guest
>   x86/hyperv: decrypt vmbus pages for sev-snp enlightened guest
>   drivers: hv: Decrypt percpu hvcall input arg page in sev-snp
>     enlightened guest
>   x86/hyperv: Initialize cpu and memory for sev-snp enlightened guest
>   x86/hyperv: SEV-SNP enlightened guest don't support legacy rtc
>   x86/hyperv: Add smp support for sev-snp guest
>   x86/hyperv: Add hyperv-specific hadling for VMMCALL under SEV-ES
>   x86/sev: Add a #HV exception handler
>   x86/sev: Add Check of #HV event in path
>   x86/sev: Initialize #HV doorbell and handle interrupt requests
> 
>  arch/x86/entry/entry_64.S             |  82 ++++++
>  arch/x86/hyperv/hv_init.c             |  43 +++
>  arch/x86/hyperv/ivm.c                 |  10 +
>  arch/x86/include/asm/cpu_entry_area.h |   6 +
>  arch/x86/include/asm/hyperv-tlfs.h    |   4 +
>  arch/x86/include/asm/idtentry.h       | 105 ++++++-
>  arch/x86/include/asm/irqflags.h       |  10 +
>  arch/x86/include/asm/mem_encrypt.h    |   2 +
>  arch/x86/include/asm/mshyperv.h       |  56 +++-
>  arch/x86/include/asm/msr-index.h      |   6 +
>  arch/x86/include/asm/page_64_types.h  |   1 +
>  arch/x86/include/asm/sev.h            |  13 +
>  arch/x86/include/asm/svm.h            |  59 +++-
>  arch/x86/include/asm/trapnr.h         |   1 +
>  arch/x86/include/asm/traps.h          |   1 +
>  arch/x86/include/asm/x86_init.h       |   2 +
>  arch/x86/include/uapi/asm/svm.h       |   4 +
>  arch/x86/kernel/cpu/common.c          |   1 +
>  arch/x86/kernel/cpu/mshyperv.c        | 228 ++++++++++++++-
>  arch/x86/kernel/dumpstack_64.c        |   9 +-
>  arch/x86/kernel/idt.c                 |   1 +
>  arch/x86/kernel/sev.c                 | 395 ++++++++++++++++++++++----
>  arch/x86/kernel/traps.c               |  42 +++
>  arch/x86/kernel/vmlinux.lds.S         |   7 +
>  arch/x86/kernel/x86_init.c            |   4 +-
>  arch/x86/mm/cpu_entry_area.c          |   2 +
>  drivers/clocksource/hyperv_timer.c    |   2 +-
>  drivers/hv/connection.c               |   1 +
>  drivers/hv/hv.c                       |  33 ++-
>  drivers/hv/hv_common.c                |  26 +-
>  include/asm-generic/hyperv-tlfs.h     |  19 ++
>  include/asm-generic/mshyperv.h        |   2 +
>  include/linux/hyperv.h                |   4 +-
>  33 files changed, 1102 insertions(+), 79 deletions(-)
>