Message ID | 20230712230202.47929-23-haitao.huang@linux.intel.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | Add Cgroup support for SGX EPC memory | expand |
Hi, On 7/12/23 16:01, Haitao Huang wrote: > From: Kristen Carlson Accardi <kristen@linux.intel.com> > > Add initial documentation of how to regulate the distribution of > SGX Enclave Page Cache (EPC) memory via the Miscellaneous cgroup > controller. > > 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> > Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com> > --- > Documentation/arch/x86/sgx.rst | 77 ++++++++++++++++++++++++++++++++++ > 1 file changed, 77 insertions(+) > > diff --git a/Documentation/arch/x86/sgx.rst b/Documentation/arch/x86/sgx.rst > index 2bcbffacbed5..f6ca5594dcf2 100644 > --- a/Documentation/arch/x86/sgx.rst > +++ b/Documentation/arch/x86/sgx.rst > @@ -300,3 +300,80 @@ to expected failures and handle them as follows: > first call. It indicates a bug in the kernel or the userspace client > if any of the second round of ``SGX_IOC_VEPC_REMOVE_ALL`` calls has > a return code other than 0. > + > + > +Cgroup Support > +============== > + > +The "sgx_epc" resource within the Miscellaneous cgroup controller regulates > +distribution of SGX EPC memory, which is a subset of system RAM that > +is used to provide SGX-enabled applications with protected memory, > +and is otherwise inaccessible, i.e. shows up as reserved in > +/proc/iomem and cannot be read/written outside of an SGX enclave. > + > +Although current systems implement EPC by stealing memory from RAM, > +for all intents and purposes the EPC is independent from normal system > +memory, e.g. must be reserved at boot from RAM and cannot be converted > +between EPC and normal memory while the system is running. The EPC is > +managed by the SGX subsystem and is not accounted by the memory > +controller. Note that this is true only for EPC memory itself, i.e. > +normal memory allocations related to SGX and EPC memory, e.g. the > +backing memory for evicted EPC pages, are accounted, limited and > +protected by the memory controller. > + > +Much like normal system memory, EPC memory can be overcommitted via > +virtual memory techniques and pages can be swapped out of the EPC > +to their backing store (normal system memory allocated via shmem). > +The SGX EPC subsystem is analogous to the memory subsytem, and > +it implements limit and protection models for EPC memory. > + > +SGX EPC Interface Files > +----------------------- > + > +For a generic description of the Miscellaneous controller interface > +files, please see Documentation/admin-guide/cgroup-v2.rst > + > +All SGX EPC memory amounts are in bytes unless explicitly stated > +otherwise. If a value which is not PAGE_SIZE aligned is written, > +the actual value used by the controller will be rounded down to > +the closest PAGE_SIZE multiple. > + > + misc.capacity > + A read-only flat-keyed file shown only in the root cgroup. > + The sgx_epc resource will show the total amount of EPC > + memory available on the platform. > + > + misc.current > + A read-only flat-keyed file shown in the non-root cgroups. > + The sgx_epc resource will show the current active EPC memory > + usage of the cgroup and its descendants. EPC pages that are > + swapped out to backing RAM are not included in the current count. > + > + misc.max > + A read-write single value file which exists on non-root > + cgroups. The sgx_epc resource will show the EPC usage > + hard limit. The default is "max". > + > + If a cgroup's EPC usage reaches this limit, EPC allocations, > + e.g. for page fault handling, will be blocked until EPC can > + be reclaimed from the cgroup. If EPC cannot be reclaimed in > + a timely manner, reclaim will be forced, e.g. by ignoring LRU. > + > + misc.events > + A read-write flat-keyed file which exists on non-root cgroups. > + Writes to the file reset the event counters to zero. A value > + change in this file generates a file modified event. > + > + max > + The number of times the cgroup has triggered a reclaim > + due to its EPC usage approaching (or exceeding) its max > + EPC boundary. The indentation here (above) is a little confusing. Is this formatted the way that is intended? > + > +Migration > +--------- > + > +Once an EPC page is charged to a cgroup (during allocation), it > +remains charged to the original cgroup until the page is released > +or reclaimed. Migrating a process to a different cgroup doesn't > +move the EPC charges that it incurred while in the previous cgroup > +to its new cgroup.
Hi On Wed, 12 Jul 2023 19:10:59 -0500, Randy Dunlap <rdunlap@infradead.org> wrote: >> + >> + >> +Cgroup Support >> +============== >> + >> +The "sgx_epc" resource within the Miscellaneous cgroup controller >> regulates >> +distribution of SGX EPC memory, which is a subset of system RAM that >> +is used to provide SGX-enabled applications with protected memory, >> +and is otherwise inaccessible, i.e. shows up as reserved in >> +/proc/iomem and cannot be read/written outside of an SGX enclave. >> + >> +Although current systems implement EPC by stealing memory from RAM, >> +for all intents and purposes the EPC is independent from normal system >> +memory, e.g. must be reserved at boot from RAM and cannot be converted >> +between EPC and normal memory while the system is running. The EPC is >> +managed by the SGX subsystem and is not accounted by the memory >> +controller. Note that this is true only for EPC memory itself, i.e. >> +normal memory allocations related to SGX and EPC memory, e.g. the >> +backing memory for evicted EPC pages, are accounted, limited and >> +protected by the memory controller. >> + >> +Much like normal system memory, EPC memory can be overcommitted via >> +virtual memory techniques and pages can be swapped out of the EPC >> +to their backing store (normal system memory allocated via shmem). >> +The SGX EPC subsystem is analogous to the memory subsytem, and >> +it implements limit and protection models for EPC memory. >> + >> +SGX EPC Interface Files >> +----------------------- >> + >> +For a generic description of the Miscellaneous controller interface >> +files, please see Documentation/admin-guide/cgroup-v2.rst >> + >> +All SGX EPC memory amounts are in bytes unless explicitly stated >> +otherwise. If a value which is not PAGE_SIZE aligned is written, >> +the actual value used by the controller will be rounded down to >> +the closest PAGE_SIZE multiple. >> + >> + misc.capacity >> + A read-only flat-keyed file shown only in the root cgroup. >> + The sgx_epc resource will show the total amount of EPC >> + memory available on the platform. >> + >> + misc.current >> + A read-only flat-keyed file shown in the non-root cgroups. >> + The sgx_epc resource will show the current active EPC memory >> + usage of the cgroup and its descendants. EPC pages that are >> + swapped out to backing RAM are not included in the current >> count. >> + >> + misc.max >> + A read-write single value file which exists on non-root >> + cgroups. The sgx_epc resource will show the EPC usage >> + hard limit. The default is "max". >> + >> + If a cgroup's EPC usage reaches this limit, EPC allocations, >> + e.g. for page fault handling, will be blocked until EPC can >> + be reclaimed from the cgroup. If EPC cannot be reclaimed in >> + a timely manner, reclaim will be forced, e.g. by ignoring LRU. >> + >> + misc.events >> + A read-write flat-keyed file which exists on non-root cgroups. >> + Writes to the file reset the event counters to zero. A value >> + change in this file generates a file modified event. >> + >> + max >> + The number of times the cgroup has triggered a reclaim >> + due to its EPC usage approaching (or exceeding) its max >> + EPC boundary. > > The indentation here (above) is a little confusing. > Is this formatted the way that is intended? > max here is an entry in the misc.events file. So it needs be indented a subsection. But I see spaces are used for indentation in sections above(misc.max, misc.current and misc.capacity), and tabs are used in this section. So I think maybe that's causing the confusing? I'll fix them using all tabs. Thanks Haitao
> + > + misc.events > + A read-write flat-keyed file which exists on non-root cgroups. It's actually read-only for this file. Will fix. Haitao
On Wed, Jul 12, 2023 at 04:01:56PM -0700, Haitao Huang wrote: > From: Kristen Carlson Accardi <kristen@linux.intel.com> > > Add initial documentation of how to regulate the distribution of > SGX Enclave Page Cache (EPC) memory via the Miscellaneous cgroup > controller. > > 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> > Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com> > --- > Documentation/arch/x86/sgx.rst | 77 ++++++++++++++++++++++++++++++++++ > 1 file changed, 77 insertions(+) > > diff --git a/Documentation/arch/x86/sgx.rst b/Documentation/arch/x86/sgx.rst > index 2bcbffacbed5..f6ca5594dcf2 100644 > --- a/Documentation/arch/x86/sgx.rst > +++ b/Documentation/arch/x86/sgx.rst > @@ -300,3 +300,80 @@ to expected failures and handle them as follows: > first call. It indicates a bug in the kernel or the userspace client > if any of the second round of ``SGX_IOC_VEPC_REMOVE_ALL`` calls has > a return code other than 0. > + > + > +Cgroup Support > +============== > + > +The "sgx_epc" resource within the Miscellaneous cgroup controller regulates > +distribution of SGX EPC memory, which is a subset of system RAM that > +is used to provide SGX-enabled applications with protected memory, > +and is otherwise inaccessible, i.e. shows up as reserved in > +/proc/iomem and cannot be read/written outside of an SGX enclave. > + > +Although current systems implement EPC by stealing memory from RAM, > +for all intents and purposes the EPC is independent from normal system > +memory, e.g. must be reserved at boot from RAM and cannot be converted > +between EPC and normal memory while the system is running. The EPC is > +managed by the SGX subsystem and is not accounted by the memory > +controller. Note that this is true only for EPC memory itself, i.e. > +normal memory allocations related to SGX and EPC memory, e.g. the > +backing memory for evicted EPC pages, are accounted, limited and > +protected by the memory controller. > + > +Much like normal system memory, EPC memory can be overcommitted via > +virtual memory techniques and pages can be swapped out of the EPC > +to their backing store (normal system memory allocated via shmem). > +The SGX EPC subsystem is analogous to the memory subsytem, and > +it implements limit and protection models for EPC memory. > + > +SGX EPC Interface Files > +----------------------- > + > +For a generic description of the Miscellaneous controller interface > +files, please see Documentation/admin-guide/cgroup-v2.rst > + > +All SGX EPC memory amounts are in bytes unless explicitly stated > +otherwise. If a value which is not PAGE_SIZE aligned is written, > +the actual value used by the controller will be rounded down to > +the closest PAGE_SIZE multiple. > + > + misc.capacity > + A read-only flat-keyed file shown only in the root cgroup. > + The sgx_epc resource will show the total amount of EPC > + memory available on the platform. > + > + misc.current > + A read-only flat-keyed file shown in the non-root cgroups. > + The sgx_epc resource will show the current active EPC memory > + usage of the cgroup and its descendants. EPC pages that are > + swapped out to backing RAM are not included in the current count. > + > + misc.max > + A read-write single value file which exists on non-root > + cgroups. The sgx_epc resource will show the EPC usage > + hard limit. The default is "max". > + > + If a cgroup's EPC usage reaches this limit, EPC allocations, > + e.g. for page fault handling, will be blocked until EPC can > + be reclaimed from the cgroup. If EPC cannot be reclaimed in > + a timely manner, reclaim will be forced, e.g. by ignoring LRU. Document the behavior when reclaim cannot happen, e.g., for the vEPC pages when a VMM tries to allocate more than misc.max. > + > + misc.events > + A read-write flat-keyed file which exists on non-root cgroups. > + Writes to the file reset the event counters to zero. A value > + change in this file generates a file modified event. > + > + max > + The number of times the cgroup has triggered a reclaim > + due to its EPC usage approaching (or exceeding) its max > + EPC boundary. > + > +Migration > +--------- > + > +Once an EPC page is charged to a cgroup (during allocation), it > +remains charged to the original cgroup until the page is released > +or reclaimed. Migrating a process to a different cgroup doesn't > +move the EPC charges that it incurred while in the previous cgroup > +to its new cgroup. > -- > 2.25.1 >
diff --git a/Documentation/arch/x86/sgx.rst b/Documentation/arch/x86/sgx.rst index 2bcbffacbed5..f6ca5594dcf2 100644 --- a/Documentation/arch/x86/sgx.rst +++ b/Documentation/arch/x86/sgx.rst @@ -300,3 +300,80 @@ to expected failures and handle them as follows: first call. It indicates a bug in the kernel or the userspace client if any of the second round of ``SGX_IOC_VEPC_REMOVE_ALL`` calls has a return code other than 0. + + +Cgroup Support +============== + +The "sgx_epc" resource within the Miscellaneous cgroup controller regulates +distribution of SGX EPC memory, which is a subset of system RAM that +is used to provide SGX-enabled applications with protected memory, +and is otherwise inaccessible, i.e. shows up as reserved in +/proc/iomem and cannot be read/written outside of an SGX enclave. + +Although current systems implement EPC by stealing memory from RAM, +for all intents and purposes the EPC is independent from normal system +memory, e.g. must be reserved at boot from RAM and cannot be converted +between EPC and normal memory while the system is running. The EPC is +managed by the SGX subsystem and is not accounted by the memory +controller. Note that this is true only for EPC memory itself, i.e. +normal memory allocations related to SGX and EPC memory, e.g. the +backing memory for evicted EPC pages, are accounted, limited and +protected by the memory controller. + +Much like normal system memory, EPC memory can be overcommitted via +virtual memory techniques and pages can be swapped out of the EPC +to their backing store (normal system memory allocated via shmem). +The SGX EPC subsystem is analogous to the memory subsytem, and +it implements limit and protection models for EPC memory. + +SGX EPC Interface Files +----------------------- + +For a generic description of the Miscellaneous controller interface +files, please see Documentation/admin-guide/cgroup-v2.rst + +All SGX EPC memory amounts are in bytes unless explicitly stated +otherwise. If a value which is not PAGE_SIZE aligned is written, +the actual value used by the controller will be rounded down to +the closest PAGE_SIZE multiple. + + misc.capacity + A read-only flat-keyed file shown only in the root cgroup. + The sgx_epc resource will show the total amount of EPC + memory available on the platform. + + misc.current + A read-only flat-keyed file shown in the non-root cgroups. + The sgx_epc resource will show the current active EPC memory + usage of the cgroup and its descendants. EPC pages that are + swapped out to backing RAM are not included in the current count. + + misc.max + A read-write single value file which exists on non-root + cgroups. The sgx_epc resource will show the EPC usage + hard limit. The default is "max". + + If a cgroup's EPC usage reaches this limit, EPC allocations, + e.g. for page fault handling, will be blocked until EPC can + be reclaimed from the cgroup. If EPC cannot be reclaimed in + a timely manner, reclaim will be forced, e.g. by ignoring LRU. + + misc.events + A read-write flat-keyed file which exists on non-root cgroups. + Writes to the file reset the event counters to zero. A value + change in this file generates a file modified event. + + max + The number of times the cgroup has triggered a reclaim + due to its EPC usage approaching (or exceeding) its max + EPC boundary. + +Migration +--------- + +Once an EPC page is charged to a cgroup (during allocation), it +remains charged to the original cgroup until the page is released +or reclaimed. Migrating a process to a different cgroup doesn't +move the EPC charges that it incurred while in the previous cgroup +to its new cgroup.