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From: Jarkko Sakkinen <jarkko@kernel.org>
To: Hillf Danton <hdanton@sina.com>
Cc: x86@kernel.org, linux-sgx@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Jethro Beekman <jethro@fortanix.com>,
	Serge Ayoun <serge.ayoun@intel.com>,
	akpm@linux-foundation.org
Subject: Re: [PATCH v41 09/24] x86/sgx: Add SGX page allocator functions
Date: Tue, 17 Nov 2020 20:14:41 +0200
Message-ID: <20201117181426.GF8524@kernel.org> (raw)
In-Reply-To: <20201114093256.7800-1-hdanton@sina.com>

On Sat, Nov 14, 2020 at 05:32:56PM +0800, Hillf Danton wrote:
> On Fri, 13 Nov 2020 00:01:20 +0200 Jarkko Sakkinen wrote:
> > 
> > The previous patch initialized a simple SGX page allocator.  Add functions
> > for runtime allocation and free.
> > 
> > This allocator and its algorithms are as simple as it gets.  They do a
> > linear search across all EPC sections and find the first free page.  They
> > are not NUMA aware and only hand out individual pages.  The SGX hardware
> > does not support large pages, so something more complicated like a buddy
> > allocator is unwarranted.
> > 
> > The free function (sgx_free_epc_page()) implicitly calls ENCLS[EREMOVE],
> > which returns the page to the uninitialized state.  This ensures that the
> > page is ready for use at the next allocation.
> > 
> > Acked-by: Jethro Beekman <jethro@fortanix.com> # v40
> > # Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com>
> > # Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> > Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
> > ---
> >  arch/x86/kernel/cpu/sgx/main.c | 65 ++++++++++++++++++++++++++++++++++
> >  arch/x86/kernel/cpu/sgx/sgx.h  |  3 ++
> >  2 files changed, 68 insertions(+)
> > 
> > diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
> > index 187a237eec38..2e53afc288a4 100644
> > --- a/arch/x86/kernel/cpu/sgx/main.c
> > +++ b/arch/x86/kernel/cpu/sgx/main.c
> > @@ -85,6 +85,71 @@ static bool __init sgx_page_reclaimer_init(void)
> >  	return true;
> >  }
> >  
> > +static struct sgx_epc_page *__sgx_alloc_epc_page_from_section(struct sgx_epc_section *section)
> > +{
> > +	struct sgx_epc_page *page;
> > +
> > +	spin_lock(&section->lock);
> > +
> > +	if (list_empty(&section->page_list)) {
> > +		spin_unlock(&section->lock);
> > +		return NULL;
> > +	}
> > +
> > +	page = list_first_entry(&section->page_list, struct sgx_epc_page, list);
> > +	list_del_init(&page->list);
> > +
> > +	spin_unlock(&section->lock);
> > +	return page;
> > +}
> > +
> > +/**
> > + * __sgx_alloc_epc_page() - Allocate an EPC page
> > + *
> > + * Iterate through EPC sections and borrow a free EPC page to the caller. When a
> > + * page is no longer needed it must be released with sgx_free_epc_page().
> > + *
> > + * Return:
> > + *   an EPC page,
> > + *   -errno on error
> > + */
> > +struct sgx_epc_page *__sgx_alloc_epc_page(void)
> > +{
> > +	struct sgx_epc_section *section;
> > +	struct sgx_epc_page *page;
> > +	int i;
> > +
> > +	for (i = 0; i < sgx_nr_epc_sections; i++) {
> > +		section = &sgx_epc_sections[i];
> > +
> > +		page = __sgx_alloc_epc_page_from_section(section);
> > +		if (page)
> > +			return page;
> > +	}
> > +
> > +	return ERR_PTR(-ENOMEM);
> > +}
> > +
> > +/**
> > + * sgx_free_epc_page() - Free an EPC page
> > + * @page:	an EPC page
> > + *
> > + * Call EREMOVE for an EPC page and insert it back to the list of free pages.
> > + */
> > +void sgx_free_epc_page(struct sgx_epc_page *page)
> > +{
> > +	struct sgx_epc_section *section = &sgx_epc_sections[page->section];
> > +	int ret;
> > +
> > +	ret = __eremove(sgx_get_epc_virt_addr(page));
> > +	if (WARN_ONCE(ret, "EREMOVE returned %d (0x%x)", ret, ret))
> > +		return;
> > +
> > +	spin_lock(&section->lock);
> > +	list_add_tail(&page->list, &section->page_list);
> 
> Add head in favor of allocators coming before LLC becomes cold.

Nice suggestion, thank you.

/Jarkko

  parent reply index

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-12 22:01 [PATCH v41 00/24] Intel SGX foundations Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 01/24] x86/sgx: Add SGX architectural data structures Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 02/24] x86/sgx: Add wrappers for ENCLS functions Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 03/24] x86/cpufeatures: x86/msr: Add Intel SGX hardware bits Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 04/24] x86/cpufeatures: x86/msr: Add Intel SGX Launch Control " Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 05/24] x86/sgx: Initialize metadata for Enclave Page Cache (EPC) sections Jarkko Sakkinen
2020-11-16 22:25   ` [PATCH] x86/sgx: clarify 'laundry_list' locking Dave Hansen
2020-11-17 19:29     ` Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 06/24] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 07/24] x86/cpu/intel: Detect SGX support Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 08/24] x86/cpu/intel: Add nosgx kernel parameter Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 09/24] x86/sgx: Add SGX page allocator functions Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 10/24] mm: Add 'mprotect' hook to struct vm_operations_struct Jarkko Sakkinen
2020-11-13 10:25   ` Mel Gorman
2020-11-17 18:16     ` Jarkko Sakkinen
2020-11-15 17:08   ` Dr. Greg
2020-11-15 17:32   ` Matthew Wilcox
2020-11-15 18:36     ` Dave Hansen
2020-11-16 10:09       ` Mel Gorman
2020-11-17 19:15         ` Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 11/24] x86/sgx: Add SGX misc driver interface Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 12/24] x86/sgx: Add SGX_IOC_ENCLAVE_CREATE Jarkko Sakkinen
     [not found]   ` <20201115044044.11040-1-hdanton@sina.com>
2020-11-17 17:35     ` Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 13/24] x86/sgx: Add SGX_IOC_ENCLAVE_ADD_PAGES Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 14/24] x86/sgx: Add SGX_IOC_ENCLAVE_INIT Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 15/24] x86/sgx: Add SGX_IOC_ENCLAVE_PROVISION Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 16/24] x86/vdso: Add support for exception fixup in vDSO functions Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 17/24] x86/fault: Add helper function to sanitize error code Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 18/24] x86/traps: Attempt to fixup exceptions in vDSO before signaling Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 19/24] x86/vdso: Implement a vDSO for Intel SGX enclave call Jarkko Sakkinen
2020-11-17 13:14   ` Borislav Petkov
2020-11-17 19:41     ` Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 20/24] selftests/x86: Add a selftest for SGX Jarkko Sakkinen
2020-11-16 18:19   ` Shuah Khan
2020-11-17 13:22     ` Borislav Petkov
2020-11-17 19:42     ` Jarkko Sakkinen
2020-11-17 17:26   ` Borislav Petkov
2020-11-17 21:27     ` Jarkko Sakkinen
2020-11-17 21:38     ` Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 21/24] x86/sgx: Add a page reclaimer Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 22/24] x86/sgx: Add ptrace() support for the SGX driver Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 23/24] docs: x86/sgx: Document SGX kernel architecture Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 24/24] x86/sgx: Update MAINTAINERS Jarkko Sakkinen
2020-11-16 16:55 ` [PATCH v41 00/24] Intel SGX foundations Borislav Petkov
2020-11-16 17:21   ` Dave Hansen
2020-11-16 17:28     ` Borislav Petkov
2020-11-17 19:20       ` Jarkko Sakkinen
     [not found] ` <20201114084211.5284-1-hdanton@sina.com>
2020-11-16 18:33   ` [PATCH v41 05/24] x86/sgx: Initialize metadata for Enclave Page Cache (EPC) sections Dave Hansen
     [not found] ` <20201115040127.7804-1-hdanton@sina.com>
2020-11-16 21:11   ` [PATCH v41 11/24] x86/sgx: Add SGX misc driver interface Dave Hansen
     [not found] ` <20201114090708.8684-1-hdanton@sina.com>
2020-11-17 18:12   ` [PATCH v41 06/24] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX Jarkko Sakkinen
     [not found] ` <20201114093256.7800-1-hdanton@sina.com>
2020-11-17 18:14   ` Jarkko Sakkinen [this message]
     [not found] ` <20201115030548.1572-1-hdanton@sina.com>
2020-11-17 18:22   ` [PATCH v41 10/24] mm: Add 'mprotect' hook to struct vm_operations_struct Jarkko Sakkinen
2020-12-15  5:38 ` [PATCH v41 00/24] Intel SGX foundations Hui, Chunyang
2020-12-15  5:43 ` Hui, Chunyang
2020-12-15 15:58   ` Jarkko Sakkinen

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