linux-kernel - Re: [PATCH v3 03/28] x86/sgx: Add 'struct sgx_epc_lru

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Date:   Mon, 17 Jul 2023 14:39:21 +0000
From:   "Jarkko Sakkinen" <jarkko@...nel.org>
To:     "Haitao Huang" <haitao.huang@...ux.intel.com>,
        <dave.hansen@...ux.intel.com>, <tj@...nel.org>,
        <linux-kernel@...r.kernel.org>, <linux-sgx@...r.kernel.org>,
        <cgroups@...r.kernel.org>, "Thomas Gleixner" <tglx@...utronix.de>,
        "Ingo Molnar" <mingo@...hat.com>, "Borislav Petkov" <bp@...en8.de>,
        <x86@...nel.org>, "H. Peter Anvin" <hpa@...or.com>
Cc:     <kai.huang@...el.com>, <reinette.chatre@...el.com>,
        "Kristen Carlson Accardi" <kristen@...ux.intel.com>,
        <zhiquan1.li@...el.com>, <seanjc@...gle.com>
Subject: Re: [PATCH v3 03/28] x86/sgx: Add 'struct sgx_epc_lru_lists' to
 encapsulate lru list(s)

On Mon Jul 17, 2023 at 1:23 PM UTC, Haitao Huang wrote:
> On Mon, 17 Jul 2023 07:45:36 -0500, Jarkko Sakkinen <jarkko@...nel.org>  
> wrote:
>
> > On Wed Jul 12, 2023 at 11:01 PM UTC, Haitao Huang wrote:
> >> From: Kristen Carlson Accardi <kristen@...ux.intel.com>
> >>
> >> 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. The new structure will be used in a following set of patches to
> >> implement SGX EPC cgroups.
> >>
> >> The changes to the structure needed for unreclaimable lists will be
> >> added in later patches.
> >>
> >> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> >> Signed-off-by: Kristen Carlson Accardi <kristen@...ux.intel.com>
> >> Signed-off-by: Haitao Huang <haitao.huang@...ux.intel.com>
> >> Cc: Sean Christopherson <seanjc@...gle.com>
> >>
> >> V3:
> >> Removed the helper functions and revised commit messages
> >> ---
> >>  arch/x86/kernel/cpu/sgx/sgx.h | 17 +++++++++++++++++
> >>  1 file changed, 17 insertions(+)
> >>
> >> diff --git a/arch/x86/kernel/cpu/sgx/sgx.h  
> >> b/arch/x86/kernel/cpu/sgx/sgx.h
> >> index f6e3c5810eef..77fceba73a25 100644
> >> --- a/arch/x86/kernel/cpu/sgx/sgx.h
> >> +++ b/arch/x86/kernel/cpu/sgx/sgx.h
> >> @@ -92,6 +92,23 @@ static inline void *sgx_get_epc_virt_addr(struct  
> >> sgx_epc_page *page)
> >>  	return section->virt_addr + index * PAGE_SIZE;
> >>  }
> >>
> >> +/*
> >> + * 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 {
> >> +	/* Must acquire this lock to access */
> >> +	spinlock_t lock;
> >
> > Isn't this self-explanatory, why the inline comment?
>
> I got a warning from the checkpatch script complaining this lock needs  
> comments.

OK, cool, not a big deal.

BR, Jarkko