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KVM: PPC: Book3S HV: Save/restore host values of debug registers

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commit 7ceaa6dcd8c6f59588428cec37f3c8093dd1011f upstream.

At present, HV KVM on POWER8 and POWER9 machines loses any instruction
or data breakpoint set in the host whenever a guest is run.
Instruction breakpoints are currently only used by xmon, but ptrace
and the perf_event subsystem can set data breakpoints as well as xmon.

To fix this, we save the host values of the debug registers (CIABR,
DAWR and DAWRX) before entering the guest and restore them on exit.
To provide space to save them in the stack frame, we expand the stack
frame allocated by kvmppc_hv_entry() from 112 to 144 bytes.

[paulus@ozlabs.org - Adjusted stack offsets since we aren't saving
 POWER9-specific registers.]

Fixes: b005255e12a3 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs", 2014-01-08)
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Paul Mackerras 2017-06-16 11:53:19 +10:00 committed by Greg Kroah-Hartman
parent 17d381054b
commit fcd35f5a3f
1 changed files with 32 additions and 7 deletions
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39
arch/powerpc/kvm/book3s_hv_rmhandlers.S
View File

@ -36,6 +36,13 @@
#define NAPPING_CEDE 1
#define NAPPING_NOVCPU 2
/* Stack frame offsets for kvmppc_hv_entry */
#define SFS 112
#define STACK_SLOT_TRAP (SFS-4)
#define STACK_SLOT_CIABR (SFS-16)
#define STACK_SLOT_DAWR (SFS-24)
#define STACK_SLOT_DAWRX (SFS-32)
/*
* Call kvmppc_hv_entry in real mode.
* Must be called with interrupts hard-disabled.
@ -274,10 +281,10 @@ kvm_novcpu_exit:
bl kvmhv_accumulate_time
#endif
13: mr r3, r12
stw r12, 112-4(r1)
stw r12, STACK_SLOT_TRAP(r1)
bl kvmhv_commence_exit
nop
lwz r12, 112-4(r1)
lwz r12, STACK_SLOT_TRAP(r1)
b kvmhv_switch_to_host
/*
@ -489,7 +496,7 @@ kvmppc_hv_entry:
*/
mflr r0
std r0, PPC_LR_STKOFF(r1)
stdu r1, -112(r1)
stdu r1, -SFS(r1)
/* Save R1 in the PACA */
std r1, HSTATE_HOST_R1(r13)
@ -643,6 +650,16 @@ kvmppc_got_guest:
mtspr SPRN_PURR,r7
mtspr SPRN_SPURR,r8
/* Save host values of some registers */
BEGIN_FTR_SECTION
mfspr r5, SPRN_CIABR
mfspr r6, SPRN_DAWR
mfspr r7, SPRN_DAWRX
std r5, STACK_SLOT_CIABR(r1)
std r6, STACK_SLOT_DAWR(r1)
std r7, STACK_SLOT_DAWRX(r1)
END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
BEGIN_FTR_SECTION
/* Set partition DABR */
/* Do this before re-enabling PMU to avoid P7 DABR corruption bug */
@ -1266,8 +1283,6 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_207S)
*/
li r0, 0
mtspr SPRN_IAMR, r0
mtspr SPRN_CIABR, r0
mtspr SPRN_DAWRX, r0
mtspr SPRN_PSPB, r0
mtspr SPRN_TCSCR, r0
mtspr SPRN_WORT, r0
@ -1426,6 +1441,16 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
slbia
ptesync
/* Restore host values of some registers */
BEGIN_FTR_SECTION
ld r5, STACK_SLOT_CIABR(r1)
ld r6, STACK_SLOT_DAWR(r1)
ld r7, STACK_SLOT_DAWRX(r1)
mtspr SPRN_CIABR, r5
mtspr SPRN_DAWR, r6
mtspr SPRN_DAWRX, r7
END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
/*
* POWER7/POWER8 guest -> host partition switch code.
* We don't have to lock against tlbies but we do
@ -1535,8 +1560,8 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
li r0, KVM_GUEST_MODE_NONE
stb r0, HSTATE_IN_GUEST(r13)
ld r0, 112+PPC_LR_STKOFF(r1)
addi r1, r1, 112
ld r0, SFS+PPC_LR_STKOFF(r1)
addi r1, r1, SFS
mtlr r0
blr