iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

powerpc/64s: remove KVM SKIP test from instruction breakpoint handler

Browse Source 
The code being executed in KVM_GUEST_MODE_SKIP is hypervisor code with
MSR[IR]=0, so the faults of concern are the d-side ones caused by access
to guest context by the hypervisor.

Instruction breakpoint interrupts are not a concern here. It's unlikely
any good would come of causing breaks in this code, but skipping the
instruction that caused it won't help matters (e.g., skip the mtmsr that
sets MSR[DR]=0 or clears KVM_GUEST_MODE_SKIP).

 [Paul notes: "the 0x1300 interrupt was dropped from the architecture a
  long time ago and is not generated by P7, P8, P9 or P10." So add a
  comment about this in the handler code while we're here. ]

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com>
Acked-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210412014845.1517916-11-npiggin@gmail.com
This commit is contained in:
Nicholas Piggin 2021-04-12 11:48:43 +10:00 committed by Michael Ellerman
parent 5eee837182
commit da487a5d1b
1 changed files with 7 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
arch/powerpc/kernel/exceptions-64s.S
View File

@ -2549,11 +2549,16 @@ EXC_REAL_NONE(0x1200, 0x100)
EXC_VIRT_NONE(0x5200, 0x100)
#endif
/**
* Interrupt 0x1300 - Instruction Address Breakpoint Interrupt.
* This has been removed from the ISA before 2.01, which is the earliest
* 64-bit BookS ISA supported, however the G5 / 970 implements this
* interrupt with a non-architected feature available through the support
* processor interface.
*/
INT_DEFINE_BEGIN(instruction_breakpoint)
IVEC=0x1300
#ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE
IKVM_SKIP=1
IKVM_REAL=1
#endif
INT_DEFINE_END(instruction_breakpoint)