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Commit a97a65d5 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
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KVM: PPC: Book3S: 64-bit CONFIG_RELOCATABLE support for interrupts 



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: default avatarNicholas Piggin <npiggin@gmail.com>
Acked-by: default avatarPaul Mackerras <paulus@ozlabs.org>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 7ede5317

arch/powerpc/include/asm/exception-64s.h

+41 −4
Original line number Diff line number Diff line
@@ -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);					\

arch/powerpc/kernel/exceptions-64s.S

+1 −1
Original line number Diff line number Diff line
@@ -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

arch/powerpc/kvm/book3s_hv_rmhandlers.S

+9 −3
Original line number Diff line number Diff line
@@ -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 +1152,12 @@ 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)

	mtctr	r3

#else

	mfctr	r3

#endif

	mfxer	r4

	std	r3, VCPU_CTR(r9)

	std	r4, VCPU_XER(r9)

arch/powerpc/kvm/book3s_segment.S

+7 −0
Original line number Diff line number Diff line
@@ -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 */