On Wed, Aug 18, 2021 at 03:29:59PM +0200, Jethro Beekman wrote:
> On 2021-08-18 15:25, Jarkko Sakkinen wrote:
> > The amount of SGX memory on the system is determined by the BIOS and it
> > varies wildly between systems. It can be from dozens of MB's on desktops
> > or VM's, up to many GB's on servers. Just like for regular memory, it is
> > sometimes useful to know the amount of usable SGX memory in the system.
> >
> > Add SGX_MemTotal field to /proc/meminfo, which shows the total amount of
> > usable SGX memory in the system. E.g. with 32 MB reserved for SGX from
> > BIOS, the printout would be:
> >
> > SGX_MemTotal: 22528 kB
> >
> > It is less than 32 MB because some of the space is reserved for Enclave
> > Page Cache Metadata (EPCM), which contains state variables for all the
> > pages in the Enclave Page Cache (EPC). The latter contains the pages,
> > which applications can use to create enclaves.
> >
> > Signed-off-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
> > ---
> > Documentation/x86/sgx.rst | 6 ++++++
> > arch/x86/include/asm/sgx.h | 10 +++++++---
> > arch/x86/kernel/cpu/sgx/main.c | 7 ++++++-
> > arch/x86/mm/pat/set_memory.c | 5 +++++
> > 4 files changed, 24 insertions(+), 4 deletions(-)
> >
> > diff --git a/Documentation/x86/sgx.rst b/Documentation/x86/sgx.rst
> > index dd0ac96ff9ef..68ee171e1d8f 100644
> > --- a/Documentation/x86/sgx.rst
> > +++ b/Documentation/x86/sgx.rst
> > @@ -250,3 +250,9 @@ user wants to deploy SGX applications both on the host and in guests
> > on the same machine, the user should reserve enough EPC (by taking out
> > total virtual EPC size of all SGX VMs from the physical EPC size) for
> > host SGX applications so they can run with acceptable performance.
> > +
> > +Supplemental fields for /proc/meminfo
> > +=====================================
> > +
> > +SGX_MemTotal
> > + The total usable SGX protected memory in kilobytes.
> > diff --git a/arch/x86/include/asm/sgx.h b/arch/x86/include/asm/sgx.h
> > index 05f3e21f01a7..2ae9dc8c9411 100644
> > --- a/arch/x86/include/asm/sgx.h
> > +++ b/arch/x86/include/asm/sgx.h
> > @@ -365,6 +365,13 @@ struct sgx_sigstruct {
> > * comment!
> > */
> >
> > +#if defined(CONFIG_X86_SGX) || defined(CONFIG_X86_SGX_KVM)
> > +extern unsigned long sgx_nr_all_pages;
> > +
> > +int sgx_set_attribute(unsigned long *allowed_attributes,
> > + unsigned int attribute_fd);
> > +#endif
> > +
> > #ifdef CONFIG_X86_SGX_KVM
> > int sgx_virt_ecreate(struct sgx_pageinfo *pageinfo, void __user *secs,
> > int *trapnr);
> > @@ -372,7 +379,4 @@ int sgx_virt_einit(void __user *sigstruct, void __user *token,
> > void __user *secs, u64 *lepubkeyhash, int *trapnr);
> > #endif
> >
> > -int sgx_set_attribute(unsigned long *allowed_attributes,
> > - unsigned int attribute_fd);
> > -
>
> This change seems unrelated?
It's just a good practice not to define symbols that do not exist, so that
if the symbol is ever used, we get a compilation error, not linking error.
Since this is included to set_memory.c, based on this conclusion, I added
the check.
/Jarkko
