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Re: [PATCH] x86/xen: avoid warning in Xen pv guest with CONFIG_AMD_MEM_ENCRYPT enabled
- To: Juergen Gross <jgross@xxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxxx>, <x86@xxxxxxxxxx>, <linux-kernel@xxxxxxxxxxxxxxx>
- From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
- Date: Mon, 25 Jan 2021 17:26:39 +0000
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On 25/01/2021 14:00, Juergen Gross wrote:
> diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
> index 4409306364dc..82948251f57b 100644
> --- a/arch/x86/xen/enlighten_pv.c
> +++ b/arch/x86/xen/enlighten_pv.c
> @@ -583,6 +583,14 @@ DEFINE_IDTENTRY_RAW(xenpv_exc_debug)
> exc_debug(regs);
> }
>
> +#ifdef CONFIG_AMD_MEM_ENCRYPT
> +DEFINE_IDTENTRY_RAW(xenpv_exc_vmm_communication)
> +{
> + /* This should never happen and there is no way to handle it. */
> + panic("X86_TRAP_VC in Xen PV mode.");
Honestly, exactly the same is true of #VE, #HV and #SX.
What we do in the hypervisor is wire up one handler for all unknown
exceptions (to avoid potential future #DF issues) leading to a panic.
Wouldn't it be better to do this unconditionally, especially as #GP/#NP
doesn't work for PV guests for unregistered callbacks, rather than
fixing up piecewise like this?
~Andrew
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