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KVM: PPC: Book3S: 64-bit CONFIG_RELOCATABLE support for interrupts

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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>
Acked-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nicholas Piggin
2017-01-27 14:00:34 +10:00
committed by Michael Ellerman
parent 7ede531773
commit a97a65d53d
4 changed files with 58 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

45
arch/powerpc/include/asm/exception-64s.h
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@@ -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); \