diff options
| author | Haren Myneni <haren@linux.ibm.com> | 2020-04-15 23:08:11 -0700 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2020-04-20 16:53:01 +1000 |
| commit | c420644c0a8f8839ca7269acbb8a3fc7fe1ec97d (patch) | |
| tree | 36c507a971a43af80e3a70537cd9ae3f75922edf /arch/powerpc/include/asm/book3s/64/mmu.h | |
| parent | 1d955f981895464d8f112179a20bfdb92e6c63d4 (diff) | |
| download | linux-c420644c0a8f8839ca7269acbb8a3fc7fe1ec97d.tar.gz linux-c420644c0a8f8839ca7269acbb8a3fc7fe1ec97d.tar.bz2 linux-c420644c0a8f8839ca7269acbb8a3fc7fe1ec97d.zip | |
powerpc: Use mm_context vas_windows counter to issue CP_ABORT
set_thread_uses_vas() sets used_vas flag for a process that opened VAS
window and issue CP_ABORT during context switch for only that process.
In multi-thread application, windows can be shared. For example Thread
A can open a window and Thread B can run COPY/PASTE instructions to
send NX request which may cause corruption or snooping or a covert
channel Also once this flag is set, continue to run CP_ABORT even the
VAS window is closed.
So define vas-windows counter in process mm_context, increment this
counter for each window open and decrement it for window close. If
vas-windows is set, issue CP_ABORT during context switch. It means
clear the foreign real address mapping only if the process / thread
uses COPY/PASTE. Then disable it for that process if windows are not
open.
Moved set_thread_uses_vas() code to vas_tx_win_open() as this
functionality is needed only for userspace open windows. We are adding
VAS userspace support along with this fix. So no need to include this
fix in stable releases.
Fixes: 9d2a4d71332c ("powerpc: Define set_thread_uses_vas()")
Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Reported-by: Nicholas Piggin <npiggin@gmail.com>
Suggested-by: Milton Miller <miltonm@us.ibm.com>
Suggested-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1587017291.2275.1077.camel@hbabu-laptop
Diffstat (limited to 'arch/powerpc/include/asm/book3s/64/mmu.h')
| -rw-r--r-- | arch/powerpc/include/asm/book3s/64/mmu.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/book3s/64/mmu.h b/arch/powerpc/include/asm/book3s/64/mmu.h index bb3deb76c951..f0a9ff690881 100644 --- a/arch/powerpc/include/asm/book3s/64/mmu.h +++ b/arch/powerpc/include/asm/book3s/64/mmu.h @@ -116,6 +116,9 @@ typedef struct { /* Number of users of the external (Nest) MMU */ atomic_t copros; + /* Number of user space windows opened in process mm_context */ + atomic_t vas_windows; + struct hash_mm_context *hash_context; unsigned long vdso_base; |