Re: [PATCH v40 03/24] x86/sgx: Initialize metadata for Enclave Page Cache (EPC) sections

[Jarkko Sakkinen]

On Wed, Nov 04, 2020 at 07:21:29PM +0100, Borislav Petkov wrote:
> On Wed, Nov 04, 2020 at 04:54:09PM +0200, Jarkko Sakkinen wrote:
> > +static void __init sgx_init(void)
> > +{
> > +	int i;
> > +
> > +	if (!boot_cpu_has(X86_FEATURE_SGX))
> 
> Guys, you need to build-test *every* *single* patch - otherwise we break
> bisectability and that is a no-no:

I've done it quite a few times (every time I've rebased my tree).  I did
today too before sending but forgot to redo git format-patch again (was
the very last thing). In my tree the order is:

e987eb0c95dd (HEAD -> master, origin/master, origin/HEAD) x86/sgx: Update MAINTAINERS
90dc0ee37f44 docs: x86/sgx: Document SGX kernel architecture
1c2e9bdab128 x86/sgx: Add ptrace() support for the SGX driver
05ce4345fb5f x86/sgx: Add a page reclaimer
94c1f778fa09 selftests/x86: Add a selftest for SGX
741b631d197b x86/vdso: Implement a vDSO for Intel SGX enclave call
5744b02641ff x86/traps: Attempt to fixup exceptions in vDSO before signaling
e957c7e79dd0 x86/fault: Add helper function to sanitize error code
96cc520b2bc9 x86/vdso: Add support for exception fixup in vDSO functions
4aff9d81b2fe x86/sgx: Add SGX_IOC_ENCLAVE_PROVISION
ea9bc917c469 x86/sgx: Add SGX_IOC_ENCLAVE_INIT
6e61e843291d x86/sgx: Add SGX_IOC_ENCLAVE_ADD_PAGES
4235ce22235e x86/sgx: Add SGX_IOC_ENCLAVE_CREATE
681299401c91 x86/sgx: Add SGX misc driver interface
fbd69fd9acf4 mm: Add 'mprotect' hook to struct vm_operations_struct
93b27a8908aa x86/sgx: Add SGX page allocator functions
5984a2ca130c x86/cpu/intel: Add nosgx kernel parameter
e131efe5ba06 x86/cpu/intel: Detect SGX support
b0bacb54d36c x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX
0c64b4c07298 x86/sgx: Initialize metadata for Enclave Page Cache (EPC) sections
358d17098c4c x86/cpufeatures: x86/msr: Add Intel SGX Launch Control hardware bits
8f7ab60e5458 x86/cpufeatures: x86/msr: Add Intel SGX hardware bits
0fb18ca935cf x86/sgx: Add wrappers for ENCLS functions
3dbc95582baf x86/sgx: Add SGX architectural data structures

I always do this before I send the patch set (or rebase my tree):

for x in {23..0}
do
git checkout master~$x
git clean -f -d -x
make tinyconfig && cat >> .config <<EOF
CONFIG_64BIT=y   
CONFIG_CRYPTO=y
CONFIG_CRYPTO_SHA256=y
CONFIG_X86_SGX=y
CONFIG_DEBUG_INFO=y
EOF
yes '' | make oldconfig && make CC="ccache gcc" -j$(nproc) || break
git --no-pager log --oneline -1 >> success.txt
done

The order is the only difference between the patch set and my tree (i.e.
diff's do not conflict between the orderings).

> arch/x86/kernel/cpu/sgx/main.c: In function ‘sgx_init’:
> arch/x86/kernel/cpu/sgx/main.c:172:20: error: ‘X86_FEATURE_SGX’ undeclared (first use in this function); did you mean ‘X86_FEATURE_SMX’?
>   172 |  if (!boot_cpu_has(X86_FEATURE_SGX))
>       |                    ^~~~~~~~~~~~~~~
> ./arch/x86/include/asm/cpufeature.h:118:24: note: in definition of macro ‘cpu_has’
>   118 |  (__builtin_constant_p(bit) && REQUIRED_MASK_BIT_SET(bit) ? 1 : \
>       |                        ^~~
> arch/x86/kernel/cpu/sgx/main.c:172:7: note: in expansion of macro ‘boot_cpu_has’
>   172 |  if (!boot_cpu_has(X86_FEATURE_SGX))
>       |       ^~~~~~~~~~~~
> arch/x86/kernel/cpu/sgx/main.c:172:20: note: each undeclared identifier is reported only once for each function it appears in
>   172 |  if (!boot_cpu_has(X86_FEATURE_SGX))
>       |                    ^~~~~~~~~~~~~~~
> ./arch/x86/include/asm/cpufeature.h:118:24: note: in definition of macro ‘cpu_has’
>   118 |  (__builtin_constant_p(bit) && REQUIRED_MASK_BIT_SET(bit) ? 1 : \
>       |                        ^~~
> arch/x86/kernel/cpu/sgx/main.c:172:7: note: in expansion of macro ‘boot_cpu_has’
>   172 |  if (!boot_cpu_has(X86_FEATURE_SGX))
>       |       ^~~~~~~~~~~~
> make[4]: *** [scripts/Makefile.build:283: arch/x86/kernel/cpu/sgx/main.o] Error 1
> make[3]: *** [scripts/Makefile.build:500: arch/x86/kernel/cpu/sgx] Error 2
> make[2]: *** [scripts/Makefile.build:500: arch/x86/kernel/cpu] Error 2
> make[2]: *** Waiting for unfinished jobs....
> make[1]: *** [scripts/Makefile.build:500: arch/x86/kernel] Error 2
> make[1]: *** Waiting for unfinished jobs....
> make: *** [Makefile:1799: arch/x86] Error 2
> make: *** Waiting for unfinished jobs....
> 
> -- 
> Regards/Gruss,
>     Boris.
> 
> https://people.kernel.org/tglx/notes-about-netiquette

/Jarkko