* [PATCH 1/3] KVM: PPC: Book3S: Change interrupt call to reduce scratch space use on HV
2016-12-21 18:29 [PATCH v2 0/3] KVM: PPC: Book3S: 64-bit CONFIG_RELOCATABLE fixes Nicholas Piggin
@ 2016-12-21 18:29 ` Nicholas Piggin
2017-01-27 2:21 ` Paul Mackerras
2016-12-21 18:29 ` [PATCH 2/3] KVM: PPC: Book3S: Move 64-bit KVM interrupt handler out from alt section Nicholas Piggin
2016-12-21 18:29 ` [PATCH 3/3] KVM: PPC: Book3S: 64-bit CONFIG_RELOCATABLE support for interrupts Nicholas Piggin
2 siblings, 1 reply; 11+ messages in thread
From: Nicholas Piggin @ 2016-12-21 18:29 UTC (permalink / raw)
To: Paul Mackerras
Cc: Nicholas Piggin, Alexander Graf, kvm-ppc, Michael Ellerman,
linuxppc-dev
Change the calling convention to put the trap number together with
CR in two halves of r12, which frees up HSTATE_SCRATCH2 in the HV
handler.
The 64-bit PR handler entry translates the calling convention back
to match the previous call convention (i.e., shared with 32-bit), for
simplicity.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/include/asm/exception-64s.h | 24 +++++++++++-------------
arch/powerpc/kvm/book3s_hv_rmhandlers.S | 16 +++++++++-------
arch/powerpc/kvm/book3s_segment.S | 25 ++++++++++++++++++-------
3 files changed, 38 insertions(+), 27 deletions(-)
diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
index 9a3eee661297..a02a268bde6b 100644
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -233,7 +233,7 @@ END_FTR_SECTION_NESTED(ftr,ftr,943)
#endif
-#define __KVM_HANDLER_PROLOG(area, n) \
+#define __KVM_HANDLER(area, h, n) \
BEGIN_FTR_SECTION_NESTED(947) \
ld r10,area+EX_CFAR(r13); \
std r10,HSTATE_CFAR(r13); \
@@ -243,30 +243,28 @@ END_FTR_SECTION_NESTED(ftr,ftr,943)
std r10,HSTATE_PPR(r13); \
END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,948); \
ld r10,area+EX_R10(r13); \
- stw r9,HSTATE_SCRATCH1(r13); \
- ld r9,area+EX_R9(r13); \
std r12,HSTATE_SCRATCH0(r13); \
-
-#define __KVM_HANDLER(area, h, n) \
- __KVM_HANDLER_PROLOG(area, n) \
- li r12,n; \
+ sldi r12,r9,32; \
+ ori r12,r12,(n); \
+ ld r9,area+EX_R9(r13); \
b kvmppc_interrupt
#define __KVM_HANDLER_SKIP(area, h, n) \
cmpwi r10,KVM_GUEST_MODE_SKIP; \
- ld r10,area+EX_R10(r13); \
beq 89f; \
- stw r9,HSTATE_SCRATCH1(r13); \
BEGIN_FTR_SECTION_NESTED(948) \
- ld r9,area+EX_PPR(r13); \
- std r9,HSTATE_PPR(r13); \
+ ld r10,area+EX_PPR(r13); \
+ std r10,HSTATE_PPR(r13); \
END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,948); \
- ld r9,area+EX_R9(r13); \
+ ld r10,area+EX_R10(r13); \
std r12,HSTATE_SCRATCH0(r13); \
- li r12,n; \
+ sldi r12,r9,32; \
+ ori r12,r12,(n); \
+ ld r9,area+EX_R9(r13); \
b kvmppc_interrupt; \
89: mtocrf 0x80,r9; \
ld r9,area+EX_R9(r13); \
+ ld r10,area+EX_R10(r13); \
b kvmppc_skip_##h##interrupt
#ifdef CONFIG_KVM_BOOK3S_64_HANDLER
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 9338a818e05c..11882aac8216 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -1057,19 +1057,18 @@ hdec_soon:
kvmppc_interrupt_hv:
/*
* Register contents:
- * R12 = interrupt vector
+ * R12 = (guest CR << 32) | interrupt vector
* R13 = PACA
- * guest CR, R12 saved in shadow VCPU SCRATCH1/0
+ * guest R12 saved in shadow VCPU SCRATCH0
* guest R13 saved in SPRN_SCRATCH0
*/
- std r9, HSTATE_SCRATCH2(r13)
-
+ std r9, HSTATE_SCRATCH1(r13)
lbz r9, HSTATE_IN_GUEST(r13)
cmpwi r9, KVM_GUEST_MODE_HOST_HV
beq kvmppc_bad_host_intr
#ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE
cmpwi r9, KVM_GUEST_MODE_GUEST
- ld r9, HSTATE_SCRATCH2(r13)
+ ld r9, HSTATE_SCRATCH1(r13)
beq kvmppc_interrupt_pr
#endif
/* We're now back in the host but in guest MMU context */
@@ -1089,13 +1088,14 @@ kvmppc_interrupt_hv:
std r6, VCPU_GPR(R6)(r9)
std r7, VCPU_GPR(R7)(r9)
std r8, VCPU_GPR(R8)(r9)
- ld r0, HSTATE_SCRATCH2(r13)
+ ld r0, HSTATE_SCRATCH1(r13)
std r0, VCPU_GPR(R9)(r9)
std r10, VCPU_GPR(R10)(r9)
std r11, VCPU_GPR(R11)(r9)
ld r3, HSTATE_SCRATCH0(r13)
- lwz r4, HSTATE_SCRATCH1(r13)
std r3, VCPU_GPR(R12)(r9)
+ /* CR is in the high half of r12 */
+ srdi r4, r12, 32
stw r4, VCPU_CR(r9)
BEGIN_FTR_SECTION
ld r3, HSTATE_CFAR(r13)
@@ -1114,6 +1114,8 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
mfspr r11, SPRN_SRR1
std r10, VCPU_SRR0(r9)
std r11, VCPU_SRR1(r9)
+ /* trap is in the low half of r12, clear CR from the high half */
+ clrldi r12, r12, 32
andi. r0, r12, 2 /* need to read HSRR0/1? */
beq 1f
mfspr r10, SPRN_HSRR0
diff --git a/arch/powerpc/kvm/book3s_segment.S b/arch/powerpc/kvm/book3s_segment.S
index ca8f174289bb..68e45080cf93 100644
--- a/arch/powerpc/kvm/book3s_segment.S
+++ b/arch/powerpc/kvm/book3s_segment.S
@@ -167,20 +167,31 @@ kvmppc_handler_trampoline_enter_end:
* *
*****************************************************************************/
-.global kvmppc_handler_trampoline_exit
-kvmppc_handler_trampoline_exit:
-
.global kvmppc_interrupt_pr
kvmppc_interrupt_pr:
+ /* 64-bit entry. Register usage at this point:
+ *
+ * SPRG_SCRATCH0 = guest R13
+ * R12 = (guest CR << 32) | exit handler id
+ * R13 = PACA
+ * HSTATE.SCRATCH0 = guest R12
+ */
+#ifdef CONFIG_PPC64
+ /* Match 32-bit entry */
+ rotldi r12, r12, 32 /* Flip R12 halves for stw */
+ stw r12, HSTATE_SCRATCH1(r13) /* CR is now in the low half */
+ srdi r12, r12, 32 /* shift trap into low half */
+#endif
+.global kvmppc_handler_trampoline_exit
+kvmppc_handler_trampoline_exit:
/* Register usage at this point:
*
- * SPRG_SCRATCH0 = guest R13
- * R12 = exit handler id
- * R13 = shadow vcpu (32-bit) or PACA (64-bit)
+ * SPRG_SCRATCH0 = guest R13
+ * R12 = exit handler id
+ * R13 = shadow vcpu (32-bit) or PACA (64-bit)
* HSTATE.SCRATCH0 = guest R12
* HSTATE.SCRATCH1 = guest CR
- *
*/
/* Save registers */
--
2.11.0
^ permalink raw reply related [flat|nested] 11+ messages in thread
* Re: [PATCH 1/3] KVM: PPC: Book3S: Change interrupt call to reduce scratch space use on HV
2016-12-21 18:29 ` [PATCH 1/3] KVM: PPC: Book3S: Change interrupt call to reduce scratch space use on HV Nicholas Piggin
@ 2017-01-27 2:21 ` Paul Mackerras
0 siblings, 0 replies; 11+ messages in thread
From: Paul Mackerras @ 2017-01-27 2:21 UTC (permalink / raw)
To: Nicholas Piggin; +Cc: Alexander Graf, kvm-ppc, Michael Ellerman, linuxppc-dev
On Thu, Dec 22, 2016 at 04:29:25AM +1000, Nicholas Piggin wrote:
> Change the calling convention to put the trap number together with
> CR in two halves of r12, which frees up HSTATE_SCRATCH2 in the HV
> handler.
>
> The 64-bit PR handler entry translates the calling convention back
> to match the previous call convention (i.e., shared with 32-bit), for
> simplicity.
>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Paul Mackerras <paulus@ozlabs.org>
I notice that I forgot to add the code to save CFAR to the
__KVM_HANDLER_SKIP macro. We should fix that.
Paul.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH 2/3] KVM: PPC: Book3S: Move 64-bit KVM interrupt handler out from alt section
2016-12-21 18:29 [PATCH v2 0/3] KVM: PPC: Book3S: 64-bit CONFIG_RELOCATABLE fixes Nicholas Piggin
2016-12-21 18:29 ` [PATCH 1/3] KVM: PPC: Book3S: Change interrupt call to reduce scratch space use on HV Nicholas Piggin
@ 2016-12-21 18:29 ` Nicholas Piggin
2017-01-27 2:25 ` Paul Mackerras
2016-12-21 18:29 ` [PATCH 3/3] KVM: PPC: Book3S: 64-bit CONFIG_RELOCATABLE support for interrupts Nicholas Piggin
2 siblings, 1 reply; 11+ messages in thread
From: Nicholas Piggin @ 2016-12-21 18:29 UTC (permalink / raw)
To: Paul Mackerras
Cc: Nicholas Piggin, Alexander Graf, kvm-ppc, Michael Ellerman,
linuxppc-dev
A subsequent patch to make KVM handlers relocation-safe makes them
unusable from within alt section "else" cases (due to the way fixed
addresses are taken from within fixed section head code).
Stop open-coding the KVM handlers, and add them both as normal. A more
optimal fix may be to allow some level of alternate feature patching in
the exception macros themselves, but for now this will do.
The TRAMP_KVM handlers must be moved to the "virt" fixed section area
(name is arbitrary) in order to be closer to .text and avoid the dreaded
"relocation truncated to fit" error.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/include/asm/head-64.h | 2 +-
arch/powerpc/kernel/exceptions-64s.S | 6 ++----
2 files changed, 3 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/include/asm/head-64.h b/arch/powerpc/include/asm/head-64.h
index fca7033839a9..9bd81619d090 100644
--- a/arch/powerpc/include/asm/head-64.h
+++ b/arch/powerpc/include/asm/head-64.h
@@ -218,7 +218,7 @@ end_##sname:
#ifdef CONFIG_KVM_BOOK3S_64_HANDLER
#define TRAMP_KVM_BEGIN(name) \
- TRAMP_REAL_BEGIN(name)
+ TRAMP_VIRT_BEGIN(name)
#else
#define TRAMP_KVM_BEGIN(name)
#endif
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index d39d6118c6e9..89b4f122aec6 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -717,13 +717,9 @@ hardware_interrupt_hv:
BEGIN_FTR_SECTION
_MASKABLE_EXCEPTION_PSERIES(0x500, hardware_interrupt_common,
EXC_HV, SOFTEN_TEST_HV)
-do_kvm_H0x500:
- KVM_HANDLER(PACA_EXGEN, EXC_HV, 0x502)
FTR_SECTION_ELSE
_MASKABLE_EXCEPTION_PSERIES(0x500, hardware_interrupt_common,
EXC_STD, SOFTEN_TEST_PR)
-do_kvm_0x500:
- KVM_HANDLER(PACA_EXGEN, EXC_STD, 0x500)
ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
EXC_REAL_END(hardware_interrupt, 0x500, 0x600)
@@ -737,6 +733,8 @@ hardware_interrupt_relon_hv:
ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE)
EXC_VIRT_END(hardware_interrupt, 0x4500, 0x4600)
+TRAMP_KVM(PACA_EXGEN, 0x500)
+TRAMP_KVM_HV(PACA_EXGEN, 0x500)
EXC_COMMON_ASYNC(hardware_interrupt_common, 0x500, do_IRQ)
--
2.11.0
^ permalink raw reply related [flat|nested] 11+ messages in thread
* Re: [PATCH 2/3] KVM: PPC: Book3S: Move 64-bit KVM interrupt handler out from alt section
2016-12-21 18:29 ` [PATCH 2/3] KVM: PPC: Book3S: Move 64-bit KVM interrupt handler out from alt section Nicholas Piggin
@ 2017-01-27 2:25 ` Paul Mackerras
0 siblings, 0 replies; 11+ messages in thread
From: Paul Mackerras @ 2017-01-27 2:25 UTC (permalink / raw)
To: Nicholas Piggin; +Cc: Alexander Graf, kvm-ppc, Michael Ellerman, linuxppc-dev
On Thu, Dec 22, 2016 at 04:29:26AM +1000, Nicholas Piggin wrote:
> A subsequent patch to make KVM handlers relocation-safe makes them
> unusable from within alt section "else" cases (due to the way fixed
> addresses are taken from within fixed section head code).
>
> Stop open-coding the KVM handlers, and add them both as normal. A more
> optimal fix may be to allow some level of alternate feature patching in
> the exception macros themselves, but for now this will do.
>
> The TRAMP_KVM handlers must be moved to the "virt" fixed section area
> (name is arbitrary) in order to be closer to .text and avoid the dreaded
> "relocation truncated to fit" error.
>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Paul Mackerras <paulus@ozlabs.org>
^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH 3/3] KVM: PPC: Book3S: 64-bit CONFIG_RELOCATABLE support for interrupts
2016-12-21 18:29 [PATCH v2 0/3] KVM: PPC: Book3S: 64-bit CONFIG_RELOCATABLE fixes Nicholas Piggin
2016-12-21 18:29 ` [PATCH 1/3] KVM: PPC: Book3S: Change interrupt call to reduce scratch space use on HV Nicholas Piggin
2016-12-21 18:29 ` [PATCH 2/3] KVM: PPC: Book3S: Move 64-bit KVM interrupt handler out from alt section Nicholas Piggin
@ 2016-12-21 18:29 ` Nicholas Piggin
2017-01-27 2:50 ` Paul Mackerras
2017-01-31 8:01 ` Paul Mackerras
2 siblings, 2 replies; 11+ messages in thread
From: Nicholas Piggin @ 2016-12-21 18:29 UTC (permalink / raw)
To: Paul Mackerras
Cc: Nicholas Piggin, Alexander Graf, kvm-ppc, Michael Ellerman,
linuxppc-dev
64-bit Book3S exception handlers must find the dynamic kernel base
to add to the target address when branching beyond __end_interrupts,
in order to support kernel running at non-0 physical address.
Support this in KVM by branching with CTR, similarly to regular
interrupt handlers. The guest CTR saved in HSTATE_SCRATCH1 and
restored after the branch.
Without this, the host kernel hangs and crashes randomly when it is
running at a non-0 address and a KVM guest is started.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/include/asm/exception-64s.h | 43 +++++++++++++++++++++++++++++---
arch/powerpc/kernel/exceptions-64s.S | 4 +--
arch/powerpc/kvm/book3s_hv_rmhandlers.S | 11 +++++---
arch/powerpc/kvm/book3s_segment.S | 7 ++++++
4 files changed, 56 insertions(+), 9 deletions(-)
diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
index a02a268bde6b..e36c741e22d5 100644
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -97,6 +97,11 @@
ld reg,PACAKBASE(r13); \
ori reg,reg,(ABS_ADDR(label))@l;
+#define __LOAD_FAR_HANDLER(reg, label) \
+ ld reg,PACAKBASE(r13); \
+ ori reg,reg,(ABS_ADDR(label))@l; \
+ addis reg,reg,(ABS_ADDR(label))@h;
+
/* Exception register prefixes */
#define EXC_HV H
#define EXC_STD
@@ -227,12 +232,44 @@ END_FTR_SECTION_NESTED(ftr,ftr,943)
mtctr reg; \
bctr
+/*
+ * KVM requires >64K branches when branching from unrelocated code.
+ */
+#define __BRANCH_TO_KVM_EXIT(area, label) \
+ mfctr r9; \
+ std r9,HSTATE_SCRATCH1(r13); \
+ __LOAD_FAR_HANDLER(r9, label); \
+ mtctr r9; \
+ ld r9,area+EX_R9(r13); \
+ bctr
+
+#define BRANCH_TO_KVM(reg, label) \
+ __LOAD_FAR_HANDLER(reg, label); \
+ mtctr reg; \
+ bctr
+
+#define BRANCH_LINK_TO_KVM(reg, label) \
+ __LOAD_FAR_HANDLER(reg, label); \
+ mtctr reg; \
+ bctrl
+
#else
#define BRANCH_TO_COMMON(reg, label) \
b label
+#define BRANCH_TO_KVM(reg, label) \
+ b label
+
+#define __BRANCH_TO_KVM_EXIT(area, label) \
+ ld r9,area+EX_R9(r13); \
+ b label
+
+#define BRANCH_LINK_TO_KVM(reg, label) \
+ bl label
+
#endif
+
#define __KVM_HANDLER(area, h, n) \
BEGIN_FTR_SECTION_NESTED(947) \
ld r10,area+EX_CFAR(r13); \
@@ -246,8 +283,7 @@ END_FTR_SECTION_NESTED(ftr,ftr,943)
std r12,HSTATE_SCRATCH0(r13); \
sldi r12,r9,32; \
ori r12,r12,(n); \
- ld r9,area+EX_R9(r13); \
- b kvmppc_interrupt
+ __BRANCH_TO_KVM_EXIT(area, kvmppc_interrupt)
#define __KVM_HANDLER_SKIP(area, h, n) \
cmpwi r10,KVM_GUEST_MODE_SKIP; \
@@ -260,8 +296,7 @@ END_FTR_SECTION_NESTED(ftr,ftr,943)
std r12,HSTATE_SCRATCH0(r13); \
sldi r12,r9,32; \
ori r12,r12,(n); \
- ld r9,area+EX_R9(r13); \
- b kvmppc_interrupt; \
+ __BRANCH_TO_KVM_EXIT(area, kvmppc_interrupt); \
89: mtocrf 0x80,r9; \
ld r9,area+EX_R9(r13); \
ld r10,area+EX_R10(r13); \
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 89b4f122aec6..d40307cfeb39 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -142,7 +142,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
lbz r0,HSTATE_HWTHREAD_REQ(r13)
cmpwi r0,0
beq 1f
- b kvm_start_guest
+ BRANCH_TO_KVM(r10, kvm_start_guest)
1:
#endif
@@ -977,7 +977,7 @@ TRAMP_REAL_BEGIN(hmi_exception_early)
EXCEPTION_PROLOG_COMMON_2(PACA_EXGEN)
EXCEPTION_PROLOG_COMMON_3(0xe60)
addi r3,r1,STACK_FRAME_OVERHEAD
- bl hmi_exception_realmode
+ BRANCH_LINK_TO_KVM(r4, hmi_exception_realmode)
/* Windup the stack. */
/* Move original HSRR0 and HSRR1 into the respective regs */
ld r9,_MSR(r1)
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 11882aac8216..c18ce740452b 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -1060,15 +1060,16 @@ kvmppc_interrupt_hv:
* R12 = (guest CR << 32) | interrupt vector
* R13 = PACA
* guest R12 saved in shadow VCPU SCRATCH0
+ * guest CTR saved in shadow VCPU SCRATCH1 if RELOCATABLE
* guest R13 saved in SPRN_SCRATCH0
*/
- std r9, HSTATE_SCRATCH1(r13)
+ std r9, HSTATE_SCRATCH2(r13)
lbz r9, HSTATE_IN_GUEST(r13)
cmpwi r9, KVM_GUEST_MODE_HOST_HV
beq kvmppc_bad_host_intr
#ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE
cmpwi r9, KVM_GUEST_MODE_GUEST
- ld r9, HSTATE_SCRATCH1(r13)
+ ld r9, HSTATE_SCRATCH2(r13)
beq kvmppc_interrupt_pr
#endif
/* We're now back in the host but in guest MMU context */
@@ -1088,7 +1089,7 @@ kvmppc_interrupt_hv:
std r6, VCPU_GPR(R6)(r9)
std r7, VCPU_GPR(R7)(r9)
std r8, VCPU_GPR(R8)(r9)
- ld r0, HSTATE_SCRATCH1(r13)
+ ld r0, HSTATE_SCRATCH2(r13)
std r0, VCPU_GPR(R9)(r9)
std r10, VCPU_GPR(R10)(r9)
std r11, VCPU_GPR(R11)(r9)
@@ -1151,7 +1152,11 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
11: stw r3,VCPU_HEIR(r9)
/* these are volatile across C function calls */
+#ifdef CONFIG_RELOCATABLE
+ ld r3, HSTATE_SCRATCH1(r13)
+#else
mfctr r3
+#endif
mfxer r4
std r3, VCPU_CTR(r9)
std r4, VCPU_XER(r9)
diff --git a/arch/powerpc/kvm/book3s_segment.S b/arch/powerpc/kvm/book3s_segment.S
index 68e45080cf93..2a2b96d53999 100644
--- a/arch/powerpc/kvm/book3s_segment.S
+++ b/arch/powerpc/kvm/book3s_segment.S
@@ -175,9 +175,16 @@ kvmppc_interrupt_pr:
* R12 = (guest CR << 32) | exit handler id
* R13 = PACA
* HSTATE.SCRATCH0 = guest R12
+ * HSTATE.SCRATCH1 = guest CTR if RELOCATABLE
*/
#ifdef CONFIG_PPC64
/* Match 32-bit entry */
+#ifdef CONFIG_RELOCATABLE
+ std r9, HSTATE_SCRATCH2(r13)
+ ld r9, HSTATE_SCRATCH1(r13)
+ mtctr r9
+ ld r9, HSTATE_SCRATCH2(r13)
+#endif
rotldi r12, r12, 32 /* Flip R12 halves for stw */
stw r12, HSTATE_SCRATCH1(r13) /* CR is now in the low half */
srdi r12, r12, 32 /* shift trap into low half */
--
2.11.0
^ permalink raw reply related [flat|nested] 11+ messages in thread
* Re: [PATCH 3/3] KVM: PPC: Book3S: 64-bit CONFIG_RELOCATABLE support for interrupts
2016-12-21 18:29 ` [PATCH 3/3] KVM: PPC: Book3S: 64-bit CONFIG_RELOCATABLE support for interrupts Nicholas Piggin
@ 2017-01-27 2:50 ` Paul Mackerras
2017-01-27 4:00 ` Nicholas Piggin
2017-01-31 8:01 ` Paul Mackerras
1 sibling, 1 reply; 11+ messages in thread
From: Paul Mackerras @ 2017-01-27 2:50 UTC (permalink / raw)
To: Nicholas Piggin; +Cc: Alexander Graf, kvm-ppc, Michael Ellerman, linuxppc-dev
On Thu, Dec 22, 2016 at 04:29:27AM +1000, Nicholas Piggin wrote:
> 64-bit Book3S exception handlers must find the dynamic kernel base
> to add to the target address when branching beyond __end_interrupts,
> in order to support kernel running at non-0 physical address.
>
> Support this in KVM by branching with CTR, similarly to regular
> interrupt handlers. The guest CTR saved in HSTATE_SCRATCH1 and
> restored after the branch.
>
> Without this, the host kernel hangs and crashes randomly when it is
> running at a non-0 address and a KVM guest is started.
>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Looks OK to me.
I have a slight quibble about the naming of the "BRANCH_LINK_TO_KVM"
macro because neither its definition nor the place where it's used
have anything to do with KVM as far as I can see. That needn't stop
the patch going in, though.
Acked-by: Paul Mackerras <paulus@ozlabs.org>
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 3/3] KVM: PPC: Book3S: 64-bit CONFIG_RELOCATABLE support for interrupts
2017-01-27 2:50 ` Paul Mackerras
@ 2017-01-27 4:00 ` Nicholas Piggin
0 siblings, 0 replies; 11+ messages in thread
From: Nicholas Piggin @ 2017-01-27 4:00 UTC (permalink / raw)
To: Paul Mackerras; +Cc: Alexander Graf, kvm-ppc, Michael Ellerman, linuxppc-dev
On Fri, 27 Jan 2017 13:50:19 +1100
Paul Mackerras <paulus@ozlabs.org> wrote:
> On Thu, Dec 22, 2016 at 04:29:27AM +1000, Nicholas Piggin wrote:
> > 64-bit Book3S exception handlers must find the dynamic kernel base
> > to add to the target address when branching beyond __end_interrupts,
> > in order to support kernel running at non-0 physical address.
> >
> > Support this in KVM by branching with CTR, similarly to regular
> > interrupt handlers. The guest CTR saved in HSTATE_SCRATCH1 and
> > restored after the branch.
> >
> > Without this, the host kernel hangs and crashes randomly when it is
> > running at a non-0 address and a KVM guest is started.
> >
> > Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
>
> Looks OK to me.
>
> I have a slight quibble about the naming of the "BRANCH_LINK_TO_KVM"
> macro because neither its definition nor the place where it's used
> have anything to do with KVM as far as I can see. That needn't stop
> the patch going in, though.
>
> Acked-by: Paul Mackerras <paulus@ozlabs.org>
No that makes sense, good point. Here's an updated patch 3 with the
hmi handler removed and some comments slightly updated (no code
changes otherwise).
I'll send the hmi relocation fix as another patch.
Thanks,
Nick
--
64-bit Book3S exception handlers must find the dynamic kernel base
to add to the target address when branching beyond __end_interrupts,
in order to support kernel running at non-0 physical address.
Support this in KVM by branching with CTR, similarly to regular
interrupt handlers. The guest CTR saved in HSTATE_SCRATCH1 and
restored after the branch.
Without this, the host kernel hangs and crashes randomly when it is
running at a non-0 address and a KVM guest is started.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/include/asm/exception-64s.h | 45 +++++++++++++++++++++++++++++---
arch/powerpc/kernel/exceptions-64s.S | 2 +-
arch/powerpc/kvm/book3s_hv_rmhandlers.S | 11 +++++---
arch/powerpc/kvm/book3s_segment.S | 7 +++++
4 files changed, 57 insertions(+), 8 deletions(-)
diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
index a02a268bde6b..9a5dbfb2d9f2 100644
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -97,6 +97,15 @@
ld reg,PACAKBASE(r13); \
ori reg,reg,(ABS_ADDR(label))@l;
+/*
+ * Branches from unrelocated code (e.g., interrupts) to labels outside
+ * head-y require >64K offsets.
+ */
+#define __LOAD_FAR_HANDLER(reg, label) \
+ ld reg,PACAKBASE(r13); \
+ ori reg,reg,(ABS_ADDR(label))@l; \
+ addis reg,reg,(ABS_ADDR(label))@h;
+
/* Exception register prefixes */
#define EXC_HV H
#define EXC_STD
@@ -227,12 +236,40 @@ END_FTR_SECTION_NESTED(ftr,ftr,943)
mtctr reg; \
bctr
+/*
+ * KVM requires __LOAD_FAR_HANDLER.
+ *
+ * __BRANCH_TO_KVM_EXIT branches are also a special case because they
+ * explicitly use r9 then reload it from PACA before branching. Hence
+ * the double-underscore.
+ */
+#define __BRANCH_TO_KVM_EXIT(area, label) \
+ mfctr r9; \
+ std r9,HSTATE_SCRATCH1(r13); \
+ __LOAD_FAR_HANDLER(r9, label); \
+ mtctr r9; \
+ ld r9,area+EX_R9(r13); \
+ bctr
+
+#define BRANCH_TO_KVM(reg, label) \
+ __LOAD_FAR_HANDLER(reg, label); \
+ mtctr reg; \
+ bctr
+
#else
#define BRANCH_TO_COMMON(reg, label) \
b label
+#define BRANCH_TO_KVM(reg, label) \
+ b label
+
+#define __BRANCH_TO_KVM_EXIT(area, label) \
+ ld r9,area+EX_R9(r13); \
+ b label
+
#endif
+
#define __KVM_HANDLER(area, h, n) \
BEGIN_FTR_SECTION_NESTED(947) \
ld r10,area+EX_CFAR(r13); \
@@ -246,8 +283,8 @@ END_FTR_SECTION_NESTED(ftr,ftr,943)
std r12,HSTATE_SCRATCH0(r13); \
sldi r12,r9,32; \
ori r12,r12,(n); \
- ld r9,area+EX_R9(r13); \
- b kvmppc_interrupt
+ /* This reloads r9 before branching to kvmppc_interrupt */ \
+ __BRANCH_TO_KVM_EXIT(area, kvmppc_interrupt)
#define __KVM_HANDLER_SKIP(area, h, n) \
cmpwi r10,KVM_GUEST_MODE_SKIP; \
@@ -260,8 +297,8 @@ END_FTR_SECTION_NESTED(ftr,ftr,943)
std r12,HSTATE_SCRATCH0(r13); \
sldi r12,r9,32; \
ori r12,r12,(n); \
- ld r9,area+EX_R9(r13); \
- b kvmppc_interrupt; \
+ /* This reloads r9 before branching to kvmppc_interrupt */ \
+ __BRANCH_TO_KVM_EXIT(area, kvmppc_interrupt); \
89: mtocrf 0x80,r9; \
ld r9,area+EX_R9(r13); \
ld r10,area+EX_R10(r13); \
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 89b4f122aec6..65a2559eeb7f 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -142,7 +142,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
lbz r0,HSTATE_HWTHREAD_REQ(r13)
cmpwi r0,0
beq 1f
- b kvm_start_guest
+ BRANCH_TO_KVM(r10, kvm_start_guest)
1:
#endif
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 11882aac8216..c18ce740452b 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -1060,15 +1060,16 @@ kvmppc_interrupt_hv:
* R12 = (guest CR << 32) | interrupt vector
* R13 = PACA
* guest R12 saved in shadow VCPU SCRATCH0
+ * guest CTR saved in shadow VCPU SCRATCH1 if RELOCATABLE
* guest R13 saved in SPRN_SCRATCH0
*/
- std r9, HSTATE_SCRATCH1(r13)
+ std r9, HSTATE_SCRATCH2(r13)
lbz r9, HSTATE_IN_GUEST(r13)
cmpwi r9, KVM_GUEST_MODE_HOST_HV
beq kvmppc_bad_host_intr
#ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE
cmpwi r9, KVM_GUEST_MODE_GUEST
- ld r9, HSTATE_SCRATCH1(r13)
+ ld r9, HSTATE_SCRATCH2(r13)
beq kvmppc_interrupt_pr
#endif
/* We're now back in the host but in guest MMU context */
@@ -1088,7 +1089,7 @@ kvmppc_interrupt_hv:
std r6, VCPU_GPR(R6)(r9)
std r7, VCPU_GPR(R7)(r9)
std r8, VCPU_GPR(R8)(r9)
- ld r0, HSTATE_SCRATCH1(r13)
+ ld r0, HSTATE_SCRATCH2(r13)
std r0, VCPU_GPR(R9)(r9)
std r10, VCPU_GPR(R10)(r9)
std r11, VCPU_GPR(R11)(r9)
@@ -1151,7 +1152,11 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
11: stw r3,VCPU_HEIR(r9)
/* these are volatile across C function calls */
+#ifdef CONFIG_RELOCATABLE
+ ld r3, HSTATE_SCRATCH1(r13)
+#else
mfctr r3
+#endif
mfxer r4
std r3, VCPU_CTR(r9)
std r4, VCPU_XER(r9)
diff --git a/arch/powerpc/kvm/book3s_segment.S b/arch/powerpc/kvm/book3s_segment.S
index 68e45080cf93..2a2b96d53999 100644
--- a/arch/powerpc/kvm/book3s_segment.S
+++ b/arch/powerpc/kvm/book3s_segment.S
@@ -175,9 +175,16 @@ kvmppc_interrupt_pr:
* R12 = (guest CR << 32) | exit handler id
* R13 = PACA
* HSTATE.SCRATCH0 = guest R12
+ * HSTATE.SCRATCH1 = guest CTR if RELOCATABLE
*/
#ifdef CONFIG_PPC64
/* Match 32-bit entry */
+#ifdef CONFIG_RELOCATABLE
+ std r9, HSTATE_SCRATCH2(r13)
+ ld r9, HSTATE_SCRATCH1(r13)
+ mtctr r9
+ ld r9, HSTATE_SCRATCH2(r13)
+#endif
rotldi r12, r12, 32 /* Flip R12 halves for stw */
stw r12, HSTATE_SCRATCH1(r13) /* CR is now in the low half */
srdi r12, r12, 32 /* shift trap into low half */
--
2.11.0
^ permalink raw reply related [flat|nested] 11+ messages in thread
* Re: [PATCH 3/3] KVM: PPC: Book3S: 64-bit CONFIG_RELOCATABLE support for interrupts
2016-12-21 18:29 ` [PATCH 3/3] KVM: PPC: Book3S: 64-bit CONFIG_RELOCATABLE support for interrupts Nicholas Piggin
2017-01-27 2:50 ` Paul Mackerras
@ 2017-01-31 8:01 ` Paul Mackerras
2017-01-31 8:17 ` Michael Ellerman
2017-01-31 10:21 ` Nicholas Piggin
1 sibling, 2 replies; 11+ messages in thread
From: Paul Mackerras @ 2017-01-31 8:01 UTC (permalink / raw)
To: Nicholas Piggin; +Cc: Alexander Graf, kvm-ppc, Michael Ellerman, linuxppc-dev
On Thu, Dec 22, 2016 at 04:29:27AM +1000, Nicholas Piggin wrote:
> 64-bit Book3S exception handlers must find the dynamic kernel base
> to add to the target address when branching beyond __end_interrupts,
> in order to support kernel running at non-0 physical address.
>
> Support this in KVM by branching with CTR, similarly to regular
> interrupt handlers. The guest CTR saved in HSTATE_SCRATCH1 and
> restored after the branch.
>
> Without this, the host kernel hangs and crashes randomly when it is
> running at a non-0 address and a KVM guest is started.
>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Unfortunately, this patch causes guests to crash in various ways when
running under a CONFIG_RELOCATABLE kernel. See below...
> diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> index 11882aac8216..c18ce740452b 100644
> --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> @@ -1060,15 +1060,16 @@ kvmppc_interrupt_hv:
> * R12 = (guest CR << 32) | interrupt vector
> * R13 = PACA
> * guest R12 saved in shadow VCPU SCRATCH0
> + * guest CTR saved in shadow VCPU SCRATCH1 if RELOCATABLE
> * guest R13 saved in SPRN_SCRATCH0
> */
> - std r9, HSTATE_SCRATCH1(r13)
> + std r9, HSTATE_SCRATCH2(r13)
> lbz r9, HSTATE_IN_GUEST(r13)
> cmpwi r9, KVM_GUEST_MODE_HOST_HV
> beq kvmppc_bad_host_intr
> #ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE
> cmpwi r9, KVM_GUEST_MODE_GUEST
> - ld r9, HSTATE_SCRATCH1(r13)
> + ld r9, HSTATE_SCRATCH2(r13)
> beq kvmppc_interrupt_pr
> #endif
> /* We're now back in the host but in guest MMU context */
> @@ -1088,7 +1089,7 @@ kvmppc_interrupt_hv:
> std r6, VCPU_GPR(R6)(r9)
> std r7, VCPU_GPR(R7)(r9)
> std r8, VCPU_GPR(R8)(r9)
> - ld r0, HSTATE_SCRATCH1(r13)
> + ld r0, HSTATE_SCRATCH2(r13)
> std r0, VCPU_GPR(R9)(r9)
> std r10, VCPU_GPR(R10)(r9)
> std r11, VCPU_GPR(R11)(r9)
> @@ -1151,7 +1152,11 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
> 11: stw r3,VCPU_HEIR(r9)
>
> /* these are volatile across C function calls */
> +#ifdef CONFIG_RELOCATABLE
> + ld r3, HSTATE_SCRATCH1(r13)
The problem is here. Depending on what sort of interrupt it is, we
can end up going back to the guest via fast_guest_return, which
doesn't reload CTR. Adding
mtctr r3
at this point makes things work.
Paul.
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 3/3] KVM: PPC: Book3S: 64-bit CONFIG_RELOCATABLE support for interrupts
2017-01-31 8:01 ` Paul Mackerras
@ 2017-01-31 8:17 ` Michael Ellerman
2017-01-31 10:21 ` Nicholas Piggin
1 sibling, 0 replies; 11+ messages in thread
From: Michael Ellerman @ 2017-01-31 8:17 UTC (permalink / raw)
To: Paul Mackerras, Nicholas Piggin; +Cc: Alexander Graf, kvm-ppc, linuxppc-dev
Paul Mackerras <paulus@ozlabs.org> writes:
> On Thu, Dec 22, 2016 at 04:29:27AM +1000, Nicholas Piggin wrote:
>> diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
>> index 11882aac8216..c18ce740452b 100644
>> --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
>> +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
>> @@ -1151,7 +1152,11 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
>> 11: stw r3,VCPU_HEIR(r9)
>>
>> /* these are volatile across C function calls */
>> +#ifdef CONFIG_RELOCATABLE
>> + ld r3, HSTATE_SCRATCH1(r13)
>
> The problem is here. Depending on what sort of interrupt it is, we
> can end up going back to the guest via fast_guest_return, which
> doesn't reload CTR. Adding
>
> mtctr r3
>
> at this point makes things work.
I folded this in.
cheers
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 3/3] KVM: PPC: Book3S: 64-bit CONFIG_RELOCATABLE support for interrupts
2017-01-31 8:01 ` Paul Mackerras
2017-01-31 8:17 ` Michael Ellerman
@ 2017-01-31 10:21 ` Nicholas Piggin
1 sibling, 0 replies; 11+ messages in thread
From: Nicholas Piggin @ 2017-01-31 10:21 UTC (permalink / raw)
To: Paul Mackerras; +Cc: Alexander Graf, kvm-ppc, Michael Ellerman, linuxppc-dev
On Tue, 31 Jan 2017 19:01:52 +1100
Paul Mackerras <paulus@ozlabs.org> wrote:
> On Thu, Dec 22, 2016 at 04:29:27AM +1000, Nicholas Piggin wrote:
> > 64-bit Book3S exception handlers must find the dynamic kernel base
> > to add to the target address when branching beyond __end_interrupts,
> > in order to support kernel running at non-0 physical address.
> >
> > Support this in KVM by branching with CTR, similarly to regular
> > interrupt handlers. The guest CTR saved in HSTATE_SCRATCH1 and
> > restored after the branch.
> >
> > Without this, the host kernel hangs and crashes randomly when it is
> > running at a non-0 address and a KVM guest is started.
> >
> > Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
>
> Unfortunately, this patch causes guests to crash in various ways when
> running under a CONFIG_RELOCATABLE kernel. See below...
>
> > diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> > index 11882aac8216..c18ce740452b 100644
> > --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> > +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> > @@ -1060,15 +1060,16 @@ kvmppc_interrupt_hv:
> > * R12 = (guest CR << 32) | interrupt vector
> > * R13 = PACA
> > * guest R12 saved in shadow VCPU SCRATCH0
> > + * guest CTR saved in shadow VCPU SCRATCH1 if RELOCATABLE
> > * guest R13 saved in SPRN_SCRATCH0
> > */
> > - std r9, HSTATE_SCRATCH1(r13)
> > + std r9, HSTATE_SCRATCH2(r13)
> > lbz r9, HSTATE_IN_GUEST(r13)
> > cmpwi r9, KVM_GUEST_MODE_HOST_HV
> > beq kvmppc_bad_host_intr
> > #ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE
> > cmpwi r9, KVM_GUEST_MODE_GUEST
> > - ld r9, HSTATE_SCRATCH1(r13)
> > + ld r9, HSTATE_SCRATCH2(r13)
> > beq kvmppc_interrupt_pr
> > #endif
> > /* We're now back in the host but in guest MMU context */
> > @@ -1088,7 +1089,7 @@ kvmppc_interrupt_hv:
> > std r6, VCPU_GPR(R6)(r9)
> > std r7, VCPU_GPR(R7)(r9)
> > std r8, VCPU_GPR(R8)(r9)
> > - ld r0, HSTATE_SCRATCH1(r13)
> > + ld r0, HSTATE_SCRATCH2(r13)
> > std r0, VCPU_GPR(R9)(r9)
> > std r10, VCPU_GPR(R10)(r9)
> > std r11, VCPU_GPR(R11)(r9)
> > @@ -1151,7 +1152,11 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
> > 11: stw r3,VCPU_HEIR(r9)
> >
> > /* these are volatile across C function calls */
> > +#ifdef CONFIG_RELOCATABLE
> > + ld r3, HSTATE_SCRATCH1(r13)
>
> The problem is here. Depending on what sort of interrupt it is, we
> can end up going back to the guest via fast_guest_return, which
> doesn't reload CTR. Adding
>
> mtctr r3
>
> at this point makes things work.
Thanks for tracking it down. Not enough testing on my end, I'm
sorry.
Thanks,
Nick
^ permalink raw reply [flat|nested] 11+ messages in thread