v2:
- This includes the backport of recently upstreamed mitigation of a CPU
vulnerability Register File Data Sampling (RFDS) (CVE-2023-28746).
This is because RFDS has a dependency on "Delay VERW" series, and it
is convenient to merge them together.
- rebased to v5.10.212
v1: https://lore.kernel.org/r/20240305-delay-verw-backport-5-10-y-v1-0-50bf452e…
This is the backport of recently upstreamed series that moves VERW
execution to a later point in exit-to-user path. This is needed because
in some cases it may be possible for data accessed after VERW executions
may end into MDS affected CPU buffers. Moving VERW closer to ring
transition reduces the attack surface.
- The series includes a dependency commit f87bc8dc7a7c ("x86/asm: Add
_ASM_RIP() macro for x86-64 (%rip) suffix").
- Patch 2 includes a change that adds runtime patching for jmp (instead
of verw in original series) due to lack of rip-relative relocation
support in kernels <v6.5.
- Fixed warning:
arch/x86/entry/entry.o: warning: objtool: mds_verw_sel+0x0: unreachable instruction.
- Resolved merge conflicts in:
syscall_return_via_sysret in entry_64.S
swapgs_restore_regs_and_return_to_usermode in entry_64.S.
__vmx_vcpu_run in vmenter.S.
vmx_update_fb_clear_dis in vmx.c.
- Boot tested with KASLR and KPTI enabled.
- Verified VERW being executed with mitigation ON.
To: stable(a)vger.kernel.org
Signed-off-by: Pawan Gupta <pawan.kumar.gupta(a)linux.intel.com>
---
H. Peter Anvin (Intel) (1):
x86/asm: Add _ASM_RIP() macro for x86-64 (%rip) suffix
Pawan Gupta (9):
x86/bugs: Add asm helpers for executing VERW
x86/entry_64: Add VERW just before userspace transition
x86/entry_32: Add VERW just before userspace transition
x86/bugs: Use ALTERNATIVE() instead of mds_user_clear static key
KVM/VMX: Move VERW closer to VMentry for MDS mitigation
x86/mmio: Disable KVM mitigation when X86_FEATURE_CLEAR_CPU_BUF is set
Documentation/hw-vuln: Add documentation for RFDS
x86/rfds: Mitigate Register File Data Sampling (RFDS)
KVM/x86: Export RFDS_NO and RFDS_CLEAR to guests
Sean Christopherson (1):
KVM/VMX: Use BT+JNC, i.e. EFLAGS.CF to select VMRESUME vs. VMLAUNCH
Documentation/ABI/testing/sysfs-devices-system-cpu | 1 +
Documentation/admin-guide/hw-vuln/index.rst | 1 +
.../admin-guide/hw-vuln/reg-file-data-sampling.rst | 104 ++++++++++++++++++++
Documentation/admin-guide/kernel-parameters.txt | 21 ++++
Documentation/x86/mds.rst | 38 +++++---
arch/x86/Kconfig | 11 +++
arch/x86/entry/entry.S | 23 +++++
arch/x86/entry/entry_32.S | 3 +
arch/x86/entry/entry_64.S | 10 ++
arch/x86/entry/entry_64_compat.S | 1 +
arch/x86/include/asm/asm.h | 5 +
arch/x86/include/asm/cpufeatures.h | 2 +
arch/x86/include/asm/entry-common.h | 1 -
arch/x86/include/asm/irqflags.h | 1 +
arch/x86/include/asm/msr-index.h | 8 ++
arch/x86/include/asm/nospec-branch.h | 27 +++---
arch/x86/kernel/cpu/bugs.c | 107 ++++++++++++++++++---
arch/x86/kernel/cpu/common.c | 38 +++++++-
arch/x86/kernel/nmi.c | 3 -
arch/x86/kvm/vmx/run_flags.h | 7 +-
arch/x86/kvm/vmx/vmenter.S | 9 +-
arch/x86/kvm/vmx/vmx.c | 12 ++-
arch/x86/kvm/x86.c | 5 +-
drivers/base/cpu.c | 8 ++
include/linux/cpu.h | 2 +
25 files changed, 394 insertions(+), 54 deletions(-)
---
base-commit: 7cfcd0ed929b28ff6942c2bee15816d08d6f7266
change-id: 20240304-delay-verw-backport-5-10-y-00aad69432f4
Best regards,
--
Thanks,
Pawan
Here's the recently merged mds improvement patches adapted to latest stable tree.
I've only compile tested them, but since I have also done similar backports for
older kernels I'm sure they should work.
The main difference is in the definition of the CLEAR_CPU_BUFFERS macro since
5.4 doesn't contains the alternative relocation handling logic hence the verw
instruction is moved out of the alternative definition and instead we have a jump which
skips the verw instruction there. That way the relocation will be handled by the
toolchain rather than the kernel.
Since I don't know if I will have time to work on the other branches this patchset
can be used as basis for the rest of the stable kernels. The main difference would be
which bit is used for CLEAR_CPU_BUFFERS. For kernel 6.6 the 2nd patch can be used verbatim
from upstrem (unlike this modified version) since the alternative relocation
did land in v6.5. However, even if used as-is from this patchset it's not a problem.
V2:
Added upstream commit id to individual patches.
H. Peter Anvin (Intel) (1):
x86/asm: Add _ASM_RIP() macro for x86-64 (%rip) suffix
Pawan Gupta (5):
x86/bugs: Add asm helpers for executing VERW
x86/entry_64: Add VERW just before userspace transition
x86/entry_32: Add VERW just before userspace transition
x86/bugs: Use ALTERNATIVE() instead of mds_user_clear static key
KVM/VMX: Move VERW closer to VMentry for MDS mitigation
Sean Christopherson (1):
KVM/VMX: Use BT+JNC, i.e. EFLAGS.CF to select VMRESUME vs. VMLAUNCH
Documentation/x86/mds.rst | 38 ++++++++++++++++++++--------
arch/x86/entry/Makefile | 2 +-
arch/x86/entry/common.c | 2 --
arch/x86/entry/entry.S | 23 +++++++++++++++++
arch/x86/entry/entry_32.S | 3 +++
arch/x86/entry/entry_64.S | 10 ++++++++
arch/x86/entry/entry_64_compat.S | 1 +
arch/x86/include/asm/asm.h | 6 ++++-
arch/x86/include/asm/cpufeatures.h | 2 +-
arch/x86/include/asm/irqflags.h | 1 +
arch/x86/include/asm/nospec-branch.h | 26 ++++++++++---------
arch/x86/kernel/cpu/bugs.c | 15 +++++------
arch/x86/kernel/nmi.c | 3 ---
arch/x86/kvm/vmx/run_flags.h | 7 +++--
arch/x86/kvm/vmx/vmenter.S | 9 ++++---
arch/x86/kvm/vmx/vmx.c | 12 ++++++---
16 files changed, 111 insertions(+), 49 deletions(-)
create mode 100644 arch/x86/entry/entry.S
--
2.34.1
v2:
- This includes the backport of recently upstreamed mitigation of a CPU
vulnerability Register File Data Sampling (RFDS) (CVE-2023-28746).
This is because RFDS has a dependency on "Delay VERW" series, and it
is convenient to merge them together.
- rebased to v5.15.151
v1: https://lore.kernel.org/r/20240304-delay-verw-backport-5-15-y-v1-0-fd02afc0…
This is the backport of recently upstreamed series that moves VERW
execution to a later point in exit-to-user path. This is needed because
in some cases it may be possible for data accessed after VERW executions
may end into MDS affected CPU buffers. Moving VERW closer to ring
transition reduces the attack surface.
- The series includes a dependency commit f87bc8dc7a7c ("x86/asm: Add
_ASM_RIP() macro for x86-64 (%rip) suffix").
- Patch 2 includes a change that adds runtime patching for jmp (instead
of verw in original series) due to lack of rip-relative relocation
support in kernels <v6.5.
- Fixed warning:
arch/x86/entry/entry.o: warning: objtool: mds_verw_sel+0x0: unreachable instruction.
- Resolved merge conflicts in:
swapgs_restore_regs_and_return_to_usermode in entry_64.S.
__vmx_vcpu_run in vmenter.S.
vmx_update_fb_clear_dis in vmx.c.
- Boot tested with KASLR and KPTI enabled.
- Verified VERW being executed with mitigation ON, and not being
executed with mitigation turned OFF.
To: stable(a)vger.kernel.org
Signed-off-by: Pawan Gupta <pawan.kumar.gupta(a)linux.intel.com>
---
---
H. Peter Anvin (Intel) (1):
x86/asm: Add _ASM_RIP() macro for x86-64 (%rip) suffix
Pawan Gupta (9):
x86/bugs: Add asm helpers for executing VERW
x86/entry_64: Add VERW just before userspace transition
x86/entry_32: Add VERW just before userspace transition
x86/bugs: Use ALTERNATIVE() instead of mds_user_clear static key
KVM/VMX: Move VERW closer to VMentry for MDS mitigation
x86/mmio: Disable KVM mitigation when X86_FEATURE_CLEAR_CPU_BUF is set
Documentation/hw-vuln: Add documentation for RFDS
x86/rfds: Mitigate Register File Data Sampling (RFDS)
KVM/x86: Export RFDS_NO and RFDS_CLEAR to guests
Sean Christopherson (1):
KVM/VMX: Use BT+JNC, i.e. EFLAGS.CF to select VMRESUME vs. VMLAUNCH
Documentation/ABI/testing/sysfs-devices-system-cpu | 1 +
Documentation/admin-guide/hw-vuln/index.rst | 1 +
.../admin-guide/hw-vuln/reg-file-data-sampling.rst | 104 ++++++++++++++++++++
Documentation/admin-guide/kernel-parameters.txt | 21 ++++
Documentation/x86/mds.rst | 38 +++++---
arch/x86/Kconfig | 11 +++
arch/x86/entry/entry.S | 23 +++++
arch/x86/entry/entry_32.S | 3 +
arch/x86/entry/entry_64.S | 11 +++
arch/x86/entry/entry_64_compat.S | 1 +
arch/x86/include/asm/asm.h | 5 +
arch/x86/include/asm/cpufeatures.h | 3 +-
arch/x86/include/asm/entry-common.h | 1 -
arch/x86/include/asm/msr-index.h | 8 ++
arch/x86/include/asm/nospec-branch.h | 27 +++---
arch/x86/kernel/cpu/bugs.c | 107 ++++++++++++++++++---
arch/x86/kernel/cpu/common.c | 38 +++++++-
arch/x86/kernel/nmi.c | 3 -
arch/x86/kvm/vmx/run_flags.h | 7 +-
arch/x86/kvm/vmx/vmenter.S | 9 +-
arch/x86/kvm/vmx/vmx.c | 12 ++-
arch/x86/kvm/x86.c | 5 +-
drivers/base/cpu.c | 8 ++
include/linux/cpu.h | 2 +
24 files changed, 394 insertions(+), 55 deletions(-)
---
base-commit: 57436264850706f50887bbb2148ee2cc797c9485
change-id: 20240304-delay-verw-backport-5-15-y-e16f07fbb71e
Best regards,
--
Thanks,
Pawan