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Re: [PATCH] x86/xen: avoid warning in Xen pv guest with CONFIG_AMD_MEM_ENCRYPT enabled

On 25.01.21 18:26, Andrew Cooper wrote:
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)
+       /* 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?

I agree it would be better to have a "catch all unknown" handler.

I'll have a try how this would look like.


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