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_SCRATCH2 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@xxxxxxxxx> --- arch/powerpc/include/asm/exception-64s.h | 39 ++++++++++++++++++++++++++++++-- arch/powerpc/include/asm/head-64.h | 2 +- arch/powerpc/kernel/exceptions-64s.S | 4 ++-- arch/powerpc/kvm/book3s_hv_rmhandlers.S | 6 +++++ arch/powerpc/kvm/book3s_segment.S | 5 ++++ 5 files changed, 51 insertions(+), 5 deletions(-) diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h index bc8fc45..000b317 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 +232,42 @@ END_FTR_SECTION_NESTED(ftr,ftr,943) mtctr reg; \ bctr +/* + * KVM requires >64K branches when branching from unrelocated code. + */ +#define BRANCH_TO_KVM_EXIT(reg, label) \ + mfctr reg; \ + std reg,HSTATE_SCRATCH2(r13); \ + __LOAD_FAR_HANDLER(reg, label); \ + mtctr reg; \ + 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(reg, label) \ + 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); \ @@ -249,7 +284,7 @@ END_FTR_SECTION_NESTED(ftr,ftr,943) or r12,r12,r9; \ ld r9,area+EX_R9(r13); \ std r9,HSTATE_SCRATCH1(r13); \ - b kvmppc_interrupt + BRANCH_TO_KVM_EXIT(r9, kvmppc_interrupt) #define __KVM_HANDLER_SKIP(area, h, n) \ cmpwi r10,KVM_GUEST_MODE_SKIP; \ @@ -265,7 +300,7 @@ END_FTR_SECTION_NESTED(ftr,ftr,943) or r12,r12,r9; \ ld r9,area+EX_R9(r13); \ std r9,HSTATE_SCRATCH1(r13); \ - b kvmppc_interrupt; \ + BRANCH_TO_KVM_EXIT(r9, kvmppc_interrupt); \ 89: mtocrf 0x80,r9; \ ld r9,area+EX_R9(r13); \ ld r10,area+EX_R10(r13); \ diff --git a/arch/powerpc/include/asm/head-64.h b/arch/powerpc/include/asm/head-64.h index f7131cf..a5cbc1c 100644 --- a/arch/powerpc/include/asm/head-64.h +++ b/arch/powerpc/include/asm/head-64.h @@ -228,7 +228,7 @@ 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 5faff1c..955fc76 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 0536c73..1d07cea 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -1047,8 +1047,14 @@ kvmppc_interrupt_hv: * R13 = PACA * R9 = unused * guest R12, R9 saved in shadow VCPU SCRATCH0/1 respectively + * guest CTR saved in shadow VCPU SCRATCH2 if RELOCATABLE * guest R13 saved in SPRN_SCRATCH0 */ +#ifdef CONFIG_RELOCATABLE + ld r9, HSTATE_SCRATCH2(r13) + mtctr r9 +#endif + lbz r9, HSTATE_IN_GUEST(r13) cmpwi r9, KVM_GUEST_MODE_HOST_HV beq kvmppc_bad_host_intr diff --git a/arch/powerpc/kvm/book3s_segment.S b/arch/powerpc/kvm/book3s_segment.S index 3b29f0f..4d25b7b 100644 --- a/arch/powerpc/kvm/book3s_segment.S +++ b/arch/powerpc/kvm/book3s_segment.S @@ -177,9 +177,14 @@ kvmppc_interrupt_pr: * R13 = PACA * HSTATE.SCRATCH0 = guest R12 * HSTATE.SCRATCH1 = guest R9 + * HSTATE.SCRATCH2 = guest CTR if RELOCATABLE */ #ifdef CONFIG_PPC64 /* Match 32-bit entry */ +#ifdef CONFIG_RELOCATABLE + ld r9,HSTATE_SCRATCH2(r13) + mtctr r9 +#endif ld r9,HSTATE_SCRATCH1(r13) stw r12,HSTATE_SCRATCH1(r13) /* CR is in the low half of r12 */ srdi r12, r12, 32 /* trap is in the high half of r12 */ -- 2.10.2 -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
