linux-kernel - RE: [PATCH v2 5/9] Drivers: hv: vmbus: Support >64 VPs for a fully enlightened TDX/SNP VM

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Message-ID: <SA1PR21MB133563B4AA42F3443E22D790BF1EA@SA1PR21MB1335.namprd21.prod.outlook.com>
Date:   Mon, 21 Aug 2023 18:17:30 +0000
From:   Dexuan Cui <decui@...rosoft.com>
To:     "Michael Kelley (LINUX)" <mikelley@...rosoft.com>,
        "ak@...ux.intel.com" <ak@...ux.intel.com>,
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Subject: RE: [PATCH v2 5/9] Drivers: hv: vmbus: Support >64 VPs for a fully
 enlightened TDX/SNP VM

> From: Michael Kelley (LINUX) <mikelley@...rosoft.com>
> Sent: Monday, August 21, 2023 7:30 AM
> [...]
> From: Dexuan Cui <decui@...rosoft.com> Sent: Sunday, August 20, 2023
> 1:27 PM
> > [...]
> > When such a VM has more than 64 VPs, if the hyperv_pcpu_input_arg is
> > not NULL, hv_common_cpu_init() -> set_memory_decrypted() -> ... ->
> > cpa_flush() -> on_each_cpu() -> ... -> hv_send_ipi_mask() -> ... ->
> > __send_ipi_mask_ex() tries to call hv_do_fast_hypercall16() with the

s/hv_do_rep_hypercall/hv_do_rep_hypercall

> Actually, it tries to call hv_do_rep_hypercall().  Using the memory-based
> hyperv_pcpu_input_arg with a "fast" hypercall doesn't make sense.

Thanks for spotting the mistake!

> > hyperv_pcpu_input_arg as the hypercall input page, which must be a
> > decrypted page in such a VM, but the page is still encrypted at this
> > point, and a fatal fault is triggered.
> >
> Modulo the minor correction in the commit message,
> 
> Reviewed-by: Michael Kelley <mikelley@...rosoft.com>

Thanks!