linux-kernel - Re: [PATCH] KVM: VMX: Always reflect SGX EPCM #PFs back into the guest

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Message-ID: <4311158801c41117a13afe0136c2807f6d9afbcd.camel@intel.com>
Date: Mon, 24 Nov 2025 00:28:14 +0000
From: "Huang, Kai" <kai.huang@...el.com>
To: "pbonzini@...hat.com" <pbonzini@...hat.com>, "seanjc@...gle.com"
	<seanjc@...gle.com>
CC: "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] KVM: VMX: Always reflect SGX EPCM #PFs back into the
 guest

On Fri, 2025-11-21 at 14:20 -0800, Sean Christopherson wrote:
> When handling intercepted #PFs, reflect EPCM (Enclave Page Cache Map)
> violations, i.e. #PFs with the SGX flag set, back into the guest.  KVM
> doesn't shadow EPCM entries (the EPCM deals only with virtual/linear
> addresses), and so EPCM violation cannot be due to KVM interference,
> and more importantly can't be resolved by KVM.
> 
> On pre-SGX2 hardware, EPCM violations are delivered as #GP(0) faults, but
> on SGX2+ hardware, they are delivered as #PF(SGX).  Failure to account for
> the SGX2 behavior could put a vCPU into an infinite loop due to KVM not
> realizing the #PF is the guest's responsibility.
> 
> Take care to deliver the EPCM violation as a #GP(0) if the _guest_ CPU
> model is only SGX1.
> 
> Fixes: 72add915fbd5 ("KVM: VMX: Enable SGX virtualization for SGX1, SGX2 and LC")
> Cc: Kai Huang <kai.huang@...el.com>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> 

Reviewed-by: Kai Huang <kai.huang@...el.com>