On 1/31/22 17:08, Sean Christopherson wrote:
Add uaccess macros for doing CMPXCHG on userspace addresses and use the
macros to fix KVM bugs by replacing flawed code that maps memory into the
kernel address space without proper mmu_notifier protection (or with
broken pfn calculations in one case).
Add yet another Kconfig for guarding asm_volatile_goto() to workaround a
clang-13 bug. I've verified the test passes on gcc versions of arm64,
PPC, RISC-V, and s390x that also pass the CC_HAS_ASM_GOTO_OUTPUT test.
Patches 1-4 are tagged for stable@ as patches 3 and 4 (mostly 3) need a
backportable fix, and doing CMPXCHG on the userspace address is the
simplest fix from a KVM perspective.
Peter Zijlstra (1):
x86/uaccess: Implement macros for CMPXCHG on user addresses
Sean Christopherson (4):
Kconfig: Add option for asm goto w/ tied outputs to workaround
clang-13 bug
KVM: x86: Use __try_cmpxchg_user() to update guest PTE A/D bits
KVM: x86: Use __try_cmpxchg_user() to emulate atomic accesses
KVM: x86: Bail to userspace if emulation of atomic user access faults
arch/x86/include/asm/uaccess.h | 131 +++++++++++++++++++++++++++++++++
arch/x86/kvm/mmu/paging_tmpl.h | 45 +----------
arch/x86/kvm/x86.c | 35 ++++-----
init/Kconfig | 4 +
4 files changed, 150 insertions(+), 65 deletions(-)
This also fixes the following syzbot issue:
https://syzkaller.appspot.com/bug?id=6cb6102a0a7b0c52060753dd62d070a1d1e71347
Tested-by: Tadeusz Struk <tadeusz.struk@xxxxxxxxxx>
--
Thanks,
Tadeusz
