| Message ID | 20180913053347.11389-1-mikey@neuling.org |
|---|---|
| State | Accepted |
| Headers | show |
| Series | KVM: PPC: Book3S HV: Fix guest r11 corruption with POWER9 TM workarounds | expand |
On Thu, 2018-09-13 at 05:33:47 UTC, Michael Neuling wrote: > When we come into the softpatch handler (0x1500), we use r11 to store > the HSRR0 for later use by the denorm handler. > > We also use the softpatch handler for the TM workarounds for > POWER9. Unfortunately, in kvmppc_interrupt_hv we later store r11 out > to the vcpu assuming it's still what we got from userspace. > > This causes r11 to be corrupted in the VCPU and hence when we restore > the guest, we get a corrupted r11. We've seen this when running TM > tests inside guests on P9. > > This fixes the problem by only touching r11 in the denorm case. > > Fixes: 4bb3c7a020 ("KVM: PPC: Book3S HV: Work around transactional memory bugs in POWER9") > Cc: <stable@vger.kernel.org> # 4.17+ > Test-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com> > Reviewed-by: Paul Mackerras <paulus@ozlabs.org> > Signed-off-by: Michael Neuling <mikey@neuling.org> Applied to powerpc fixes, thanks. https://git.kernel.org/powerpc/c/f14040bca89258b8a1c71e2112e430 cheers
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index ea04dfb8c0..2d8fc8c9da 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -1314,9 +1314,7 @@ EXC_REAL_BEGIN(denorm_exception_hv, 0x1500, 0x100) #ifdef CONFIG_PPC_DENORMALISATION mfspr r10,SPRN_HSRR1 - mfspr r11,SPRN_HSRR0 /* save HSRR0 */ andis. r10,r10,(HSRR1_DENORM)@h /* denorm? */ - addi r11,r11,-4 /* HSRR0 is next instruction */ bne+ denorm_assist #endif @@ -1382,6 +1380,8 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_207S) */ XVCPSGNDP32(32) denorm_done: + mfspr r11,SPRN_HSRR0 + subi r11,r11,4 mtspr SPRN_HSRR0,r11 mtcrf 0x80,r9 ld r9,PACA_EXGEN+EX_R9(r13)
When we come into the softpatch handler (0x1500), we use r11 to store the HSRR0 for later use by the denorm handler. We also use the softpatch handler for the TM workarounds for POWER9. Unfortunately, in kvmppc_interrupt_hv we later store r11 out to the vcpu assuming it's still what we got from userspace. This causes r11 to be corrupted in the VCPU and hence when we restore the guest, we get a corrupted r11. We've seen this when running TM tests inside guests on P9. This fixes the problem by only touching r11 in the denorm case. Fixes: 4bb3c7a020 ("KVM: PPC: Book3S HV: Work around transactional memory bugs in POWER9") Cc: <stable@vger.kernel.org> # 4.17+ Test-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com> Reviewed-by: Paul Mackerras <paulus@ozlabs.org> Signed-off-by: Michael Neuling <mikey@neuling.org> --- arch/powerpc/kernel/exceptions-64s.S | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)