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 06/24] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX
Date: Tue, 17 Nov 2020 20:12:58 +0200 [thread overview]
Message-ID: <20201117181258.GE8524@kernel.org> (raw)
In-Reply-To: <20201114090708.8684-1-hdanton@sina.com>
On Sat, Nov 14, 2020 at 05:07:08PM +0800, Hillf Danton wrote:
> On Fri, 13 Nov 2020 00:01:17 +0200
> >
> > From: Sean Christopherson <sean.j.christopherson@intel.com>
> >
> > The x86 architecture has a set of page fault error codes. These indicate
> > things like whether the fault occurred from a write, or whether it
> > originated in userspace.
> >
> > The SGX hardware architecture has its own per-page memory management
> > metadata (EPCM) [*] and hardware which is separate from the normal x86 MMU.
> > The architecture has a new page fault error code: PF_SGX. This new error
> > code bit is set whenever a page fault occurs as the result of the SGX MMU.
> >
> > These faults occur for a variety of reasons. For instance, an access
> > attempt to enclave memory from outside the enclave causes a PF_SGX fault.
> > PF_SGX would also be set for permission conflicts, such as if a write to an
> > enclave page occurs and the page is marked read-write in the x86 page
> > tables but is read-only in the EPCM.
> >
> > These faults do not always indicate errors, though. SGX pages are
> > encrypted with a key that is destroyed at hardware reset, including
> > suspend. Throwing a SIGSEGV allows user space software to react and recover
> > when these events occur.
> >
> > Include PF_SGX in the PF error codes list and throw SIGSEGV when it is
> > encountered.
> >
> > [*] Intel SDM: 36.5.1 Enclave Page Cache Map (EPCM)
> >
> > Acked-by: Jethro Beekman <jethro@fortanix.com> # v40
> > # Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> > Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
> > ---
> > arch/x86/include/asm/trap_pf.h | 1 +
> > arch/x86/mm/fault.c | 12 ++++++++++++
> > 2 files changed, 13 insertions(+)
> >
> > diff --git a/arch/x86/include/asm/trap_pf.h b/arch/x86/include/asm/trap_pf.h
> > index 305bc1214aef..1794777b2a85 100644
> > --- a/arch/x86/include/asm/trap_pf.h
> > +++ b/arch/x86/include/asm/trap_pf.h
> > @@ -19,6 +19,7 @@ enum x86_pf_error_code {
> > X86_PF_RSVD = 1 << 3,
> > X86_PF_INSTR = 1 << 4,
> > X86_PF_PK = 1 << 5,
> > + X86_PF_SGX = 1 << 15,
> > };
> >
> > #endif /* _ASM_X86_TRAP_PF_H */
> > diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
> > index 82bf37a5c9ec..9339fee83784 100644
> > --- a/arch/x86/mm/fault.c
> > +++ b/arch/x86/mm/fault.c
> > @@ -1101,6 +1101,18 @@ access_error(unsigned long error_code, struct vm_area_struct *vma)
> > if (error_code & X86_PF_PK)
> > return 1;
> >
> > + /*
> > + * SGX hardware blocked the access. This usually happens
> > + * when the enclave memory contents have been destroyed, like
> > + * after a suspend/resume cycle. In any case, the kernel can't
> > + * fix the cause of the fault. Handle the fault as an access
> > + * error even in cases where no actual access violation
> > + * occurred. This allows userspace to rebuild the enclave in
> > + * response to the signal.
> > + */
>
> Given SIGSEGV, it helps much understand PF_SGX to specify the rebuild
> in userspace a bit more.
I'm sorry but I'm not exactly sure what you are suggesting.
/Jarkko
next prev parent reply other threads:[~2020-11-17 18:13 UTC|newest]
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 ` Jarkko Sakkinen [this message]
[not found] ` <20201114093256.7800-1-hdanton@sina.com>
2020-11-17 18:14 ` [PATCH v41 09/24] x86/sgx: Add SGX page allocator functions Jarkko Sakkinen
[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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