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Message-ID: <f2236b51-400a-b300-e818-297e45cc7b49@intel.com>
Date:   Thu, 22 Sep 2022 14:39:53 -0700
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Subject: Re: [RFC PATCH 03/20] x86/sgx: Track owning enclave in VA EPC pages
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To:     Kristen Carlson Accardi <kristen@linux.intel.com>,
        linux-kernel@vger.kernel.org, linux-sgx@vger.kernel.org,
        cgroups@vger.kernel.org, Jarkko Sakkinen <jarkko@kernel.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>
Cc:     Sean Christopherson <seanjc@google.com>
References: <20220922171057.1236139-1-kristen@linux.intel.com>
 <20220922171057.1236139-4-kristen@linux.intel.com>
 <1adb03c8-1274-3898-0677-03015a1f5a5d@intel.com>
 <f031ac1bd6b16509f1d714cd65e6b017f054940c.camel@linux.intel.com>
From:   Dave Hansen <dave.hansen@intel.com>
In-Reply-To: <f031ac1bd6b16509f1d714cd65e6b017f054940c.camel@linux.intel.com>
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On 9/22/22 13:04, Kristen Carlson Accardi wrote:
>> BTW, is there a flag or any other way to tell to what kind of object
>> ->owner points?
> The owner will only be an sgx_encl type if it is a va page, so to tell
> what kind of object owner is, you look at the epc page flags - like
> this:
>         if (epc_page->flags & SGX_EPC_PAGE_ENCLAVE)
>                 encl = ((struct sgx_encl_page *)epc_page->owner)->encl;
>         else if (epc_page->flags & SGX_EPC_PAGE_VERSION_ARRAY)
>                 encl = epc_page->owner;
> ...

I don't know how much refactoring it would take, but it would be nice if
that was a bit more obvious.  Basically, can we get the code that checks
for or sets SGX_EPC_PAGE_VERSION_ARRAY close to the code that assigns or
reads ->owner?