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

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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.

Fixes: b005255e12 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs", 2014-01-08)
Cc: stable@vger.kernel.org # v3.14+
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This commit is contained in:
Paul Mackerras 2017-06-16 11:53:19 +10:00
parent 46a704f840
commit 7ceaa6dcd8
1 changed files with 32 additions and 13 deletions
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45
arch/powerpc/kvm/book3s_hv_rmhandlers.S
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@ -44,6 +44,17 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
#define NAPPING_CEDE 1
#define NAPPING_NOVCPU 2
/* Stack frame offsets for kvmppc_hv_entry */
#define SFS 144
#define STACK_SLOT_TRAP (SFS-4)
#define STACK_SLOT_TID (SFS-16)
#define STACK_SLOT_PSSCR (SFS-24)
#define STACK_SLOT_PID (SFS-32)
#define STACK_SLOT_IAMR (SFS-40)
#define STACK_SLOT_CIABR (SFS-48)
#define STACK_SLOT_DAWR (SFS-56)
#define STACK_SLOT_DAWRX (SFS-64)
/*
* Call kvmppc_hv_entry in real mode.
* Must be called with interrupts hard-disabled.
@ -328,10 +339,10 @@ 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
/*
@ -554,12 +565,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
* *
*****************************************************************************/
/* Stack frame offsets */
#define STACK_SLOT_TID (112-16)
#define STACK_SLOT_PSSCR (112-24)
#define STACK_SLOT_PID (112-32)
#define STACK_SLOT_IAMR (112-40)
.global kvmppc_hv_entry
kvmppc_hv_entry:
@ -575,7 +580,7 @@ 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)
@ -765,6 +770,14 @@ BEGIN_FTR_SECTION
std r7, STACK_SLOT_PID(r1)
std r8, STACK_SLOT_IAMR(r1)
END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
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 */
@ -1518,8 +1531,6 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_300)
* set by the guest could disrupt the host.
*/
li r0, 0
mtspr SPRN_CIABR, r0
mtspr SPRN_DAWRX, r0
mtspr SPRN_PSPB, r0
mtspr SPRN_WORT, r0
BEGIN_FTR_SECTION
@ -1684,6 +1695,14 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
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)
BEGIN_FTR_SECTION
ld r5, STACK_SLOT_TID(r1)
ld r6, STACK_SLOT_PSSCR(r1)
@ -1836,8 +1855,8 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_TYPE_RADIX)
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