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Message-ID: <08a420401b2fb539f37cbf21a0ded6bf8c68c72b.camel@linux.intel.com>
Subject: Re: [PATCH v2 03/18] x86/sgx: Add 'struct sgx_epc_lru_lists' to
 encapsulate lru list(s)
From:   Kristen Carlson Accardi <kristen@linux.intel.com>
To:     Jarkko Sakkinen <jarkko@kernel.org>
Cc:     dave.hansen@linux.intel.com, tj@kernel.org,
        linux-kernel@vger.kernel.org, linux-sgx@vger.kernel.org,
        cgroups@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
        zhiquan1.li@intel.com, Sean Christopherson <seanjc@google.com>
Date:   Thu, 08 Dec 2022 10:03:04 -0800
In-Reply-To: <Y5IDXF+6GmURxbYF@kernel.org>
References: <20221202183655.3767674-1-kristen@linux.intel.com>
         <20221202183655.3767674-4-kristen@linux.intel.com>
         <Y5IDXF+6GmURxbYF@kernel.org>
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On Thu, 2022-12-08 at 15:31 +0000, Jarkko Sakkinen wrote:
> On Fri, Dec 02, 2022 at 10:36:39AM -0800, Kristen Carlson Accardi
> wrote:
> > Introduce a data structure to wrap the existing reclaimable list
> > and its spinlock in a struct to minimize the code changes needed
> > to handle multiple LRUs as well as reclaimable and non-reclaimable
> > lists, both of which will be introduced and used by SGX EPC
> > cgroups.
> >=20
> > Signed-off-by: Sean Christopherson
> > <sean.j.christopherson@intel.com>
> > Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
> > Cc: Sean Christopherson <seanjc@google.com>
> > ---
> > =C2=A0arch/x86/kernel/cpu/sgx/sgx.h | 65
> > +++++++++++++++++++++++++++++++++++
> > =C2=A01 file changed, 65 insertions(+)
> >=20
> > diff --git a/arch/x86/kernel/cpu/sgx/sgx.h
> > b/arch/x86/kernel/cpu/sgx/sgx.h
> > index 39cb15a8abcb..5e6d88438fae 100644
> > --- a/arch/x86/kernel/cpu/sgx/sgx.h
> > +++ b/arch/x86/kernel/cpu/sgx/sgx.h
> > @@ -90,6 +90,71 @@ static inline void *sgx_get_epc_virt_addr(struct
> > sgx_epc_page *page)
> > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0return section->virt_ad=
dr + index * PAGE_SIZE;
> > =C2=A0}
> > =C2=A0
> > +/*
> > + * This data structure wraps a list of reclaimable EPC pages, and
> > a list of
> > + * non-reclaimable EPC pages and is used to implement a LRU policy
> > during
> > + * reclamation.
> > + */
> > +struct sgx_epc_lru_lists {
> > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0spinlock_t lock;
> > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0struct list_head reclaimable=
;
> > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0struct list_head unreclaimab=
le;
> > +};
> =C2=A0
> Why this is named like this, and not sgx_epc_global_rcu? Are there
> any other use cases?
>=20
> BR, Jarkko

Yes, there are other use cases that are introduced in the other
patches. This structure is used to in the cgroup struct to hold cgroup
specific LRUs.