Move the GUEST_MODE_SKIP logic into KVM code. This is quite a KVM
internal detail that has no real need to be in common handlers.
Also add a comment explaining why this this thing exists.
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
arch/powerpc/kernel/exceptions-64s.S | 60 --------------------------
arch/powerpc/kvm/book3s_64_entry.S | 64 ++++++++++++++++++++++++----
2 files changed, 56 insertions(+), 68 deletions(-)
diff --git a/arch/powerpc/kernel/exceptions-64s.S
b/arch/powerpc/kernel/exceptions-64s.S
index a1640d6ea65d..96f22c582213 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -133,7 +133,6 @@ name:
#define IBRANCH_TO_COMMON .L_IBRANCH_TO_COMMON_\name\() /* ENTRY branch
to common */
#define IREALMODE_COMMON .L_IREALMODE_COMMON_\name\() /* Common runs in
realmode */
#define IMASK .L_IMASK_\name\() /* IRQ soft-mask bit */
-#define IKVM_SKIP .L_IKVM_SKIP_\name\() /* Generate KVM skip handler */
#define IKVM_REAL .L_IKVM_REAL_\name\() /* Real entry tests KVM */
#define __IKVM_REAL(name) .L_IKVM_REAL_ ## name
#define IKVM_VIRT .L_IKVM_VIRT_\name\() /* Virt entry tests KVM */
@@ -191,9 +190,6 @@ do_define_int n
.ifndef IMASK
IMASK=0
.endif
- .ifndef IKVM_SKIP
- IKVM_SKIP=0
- .endif
.ifndef IKVM_REAL
IKVM_REAL=0
.endif
@@ -254,15 +250,10 @@ do_define_int n
.balign IFETCH_ALIGN_BYTES
\name\()_kvm:
- .if IKVM_SKIP
- cmpwi r10,KVM_GUEST_MODE_SKIP
- beq 89f
- .else
BEGIN_FTR_SECTION
ld r10,IAREA+EX_CFAR(r13)
std r10,HSTATE_CFAR(r13)
END_FTR_SECTION_IFSET(CPU_FTR_CFAR)
- .endif
ld r10,IAREA+EX_CTR(r13)
mtctr r10
@@ -289,27 +280,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
ori r12,r12,(IVEC)
.endif
b kvmppc_interrupt
-
- .if IKVM_SKIP
-89: mtocrf 0x80,r9
- ld r10,IAREA+EX_CTR(r13)
- mtctr r10
- ld r9,IAREA+EX_R9(r13)
- ld r10,IAREA+EX_R10(r13)
- ld r11,IAREA+EX_R11(r13)
- ld r12,IAREA+EX_R12(r13)
- .if IHSRR_IF_HVMODE
- BEGIN_FTR_SECTION
- b kvmppc_skip_Hinterrupt
- FTR_SECTION_ELSE
- b kvmppc_skip_interrupt
- ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
- .elseif IHSRR
- b kvmppc_skip_Hinterrupt
- .else
- b kvmppc_skip_interrupt
- .endif
- .endif
.endm
#else
@@ -1128,7 +1098,6 @@ INT_DEFINE_BEGIN(machine_check)
ISET_RI=0
IDAR=1
IDSISR=1
- IKVM_SKIP=1
IKVM_REAL=1
INT_DEFINE_END(machine_check)
@@ -1419,7 +1388,6 @@ INT_DEFINE_BEGIN(data_access)
IVEC=0x300
IDAR=1
IDSISR=1
- IKVM_SKIP=1
IKVM_REAL=1
INT_DEFINE_END(data_access)
@@ -1465,7 +1433,6 @@ INT_DEFINE_BEGIN(data_access_slb)
IVEC=0x380
IRECONCILE=0
IDAR=1
- IKVM_SKIP=1
IKVM_REAL=1
INT_DEFINE_END(data_access_slb)
@@ -2111,7 +2078,6 @@ INT_DEFINE_BEGIN(h_data_storage)
IHSRR=1
IDAR=1
IDSISR=1
- IKVM_SKIP=1
IKVM_REAL=1
IKVM_VIRT=1
INT_DEFINE_END(h_data_storage)
@@ -3088,32 +3054,6 @@ EXPORT_SYMBOL(do_uaccess_flush)
MASKED_INTERRUPT
MASKED_INTERRUPT hsrr=1
-#ifdef CONFIG_KVM_BOOK3S_64_HANDLER
-kvmppc_skip_interrupt:
- /*
- * Here all GPRs are unchanged from when the interrupt happened
- * except for r13, which is saved in SPRG_SCRATCH0.
- */
- mfspr r13, SPRN_SRR0
- addi r13, r13, 4
- mtspr SPRN_SRR0, r13
- GET_SCRATCH0(r13)
- RFI_TO_KERNEL
- b .
-
-kvmppc_skip_Hinterrupt:
- /*
- * Here all GPRs are unchanged from when the interrupt happened
- * except for r13, which is saved in SPRG_SCRATCH0.
- */
- mfspr r13, SPRN_HSRR0
- addi r13, r13, 4
- mtspr SPRN_HSRR0, r13
- GET_SCRATCH0(r13)
- HRFI_TO_KERNEL
- b .
-#endif
-
/*
* Relocation-on interrupts: A subset of the interrupts can be delivered
* with IR=1/DR=1, if AIL==2 and MSR.HV won't be changed by delivering
diff --git a/arch/powerpc/kvm/book3s_64_entry.S
b/arch/powerpc/kvm/book3s_64_entry.S
index 147ebf1c3c1f..820d103e5f50 100644
--- a/arch/powerpc/kvm/book3s_64_entry.S
+++ b/arch/powerpc/kvm/book3s_64_entry.S
@@ -1,9 +1,10 @@
+#include <asm/asm-offsets.h>
#include <asm/cache.h>
-#include <asm/ppc_asm.h>
+#include <asm/exception-64s.h>
#include <asm/kvm_asm.h>
-#include <asm/reg.h>
-#include <asm/asm-offsets.h>
#include <asm/kvm_book3s_asm.h>
+#include <asm/ppc_asm.h>
+#include <asm/reg.h>
/*
* This is branched to from interrupt handlers in exception-64s.S which set
@@ -19,17 +20,64 @@ kvmppc_interrupt:
* guest R12 saved in shadow VCPU SCRATCH0
* guest R13 saved in SPRN_SCRATCH0
*/
+ std r9,HSTATE_SCRATCH2(r13)
+ lbz r9,HSTATE_IN_GUEST(r13)
+ cmpwi r9,KVM_GUEST_MODE_SKIP
+ beq- .Lmaybe_skip
+.Lno_skip:
#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
- std r9, HSTATE_SCRATCH2(r13)
- lbz r9, HSTATE_IN_GUEST(r13)
- cmpwi r9, KVM_GUEST_MODE_HOST_HV
+ 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)
+ cmpwi r9,KVM_GUEST_MODE_GUEST
+ ld r9,HSTATE_SCRATCH2(r13)
beq kvmppc_interrupt_pr
#endif
b kvmppc_interrupt_hv
#else
b kvmppc_interrupt_pr
#endif
+
+/*
+ * KVM uses a trick where it is running in MSR[HV]=1 mode in real-mode with the
+ * guest MMU context loaded, and it sets KVM_GUEST_MODE_SKIP and enables
+ * MSR[DR]=1 while leaving MSR[IR]=0, so it continues to fetch HV instructions
+ * but loads and stores will access the guest context. This is used to load
+ * the faulting instruction without walking page tables.
+ *
+ * However the guest context may not be able to translate, or it may cause a
+ * machine check or other issue, which will result in a fault in the host
+ * (even with KVM-HV).
+ *
+ * These faults are caught here and if the fault was (or was likely) due to
+ * that load, then we just return with the PC advanced +4 and skip the load,
+ * which then goes via the slow path.
+ */
+.Lmaybe_skip:
+ cmpwi r12,BOOK3S_INTERRUPT_MACHINE_CHECK
+ beq 1f
+ cmpwi r12,BOOK3S_INTERRUPT_DATA_STORAGE
+ beq 1f
+ cmpwi r12,BOOK3S_INTERRUPT_DATA_SEGMENT
+ beq 1f
+#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
+ cmpwi r12,BOOK3S_INTERRUPT_H_DATA_STORAGE | 0x2
+ beq 2f
+#endif
+ b .Lno_skip
+1: mfspr r9,SPRN_SRR0
+ addi r9,r9,4
+ mtspr SPRN_SRR0,r9
+ ld r12,HSTATE_SCRATCH0(r13)
+ ld r9,HSTATE_SCRATCH2(r13)
+ GET_SCRATCH0(r13)
+ RFI_TO_KERNEL
+#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
+2: mfspr r9,SPRN_HSRR0
+ addi r9,r9,4
+ mtspr SPRN_HSRR0,r9
+ ld r12,HSTATE_SCRATCH0(r13)
+ ld r9,HSTATE_SCRATCH2(r13)
+ GET_SCRATCH0(r13)
+ HRFI_TO_KERNEL
+#endif
--
2.23.0
