Commit f14040bc authored Sep 13, 2018 by Michael Neuling Committed by Michael Ellerman Sep 17, 2018

KVM: PPC: Book3S HV: Fix guest r11 corruption with POWER9 TM workarounds



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: 4bb3c7a0 ("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>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

parent 11da3a7f

arch/powerpc/kernel/exceptions-64s.S

+2 −2

Original line number	Diff line number	Diff line
		@@ -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)