linux/arch/powerpc/include/asm/kvm_booke_hv_asm.h

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/*
* Copyright 2010-2011 Freescale Semiconductor, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License, version 2, as
* published by the Free Software Foundation.
*/
#ifndef ASM_KVM_BOOKE_HV_ASM_H
#define ASM_KVM_BOOKE_HV_ASM_H
#ifdef __ASSEMBLY__
/*
* All exceptions from guest state must go through KVM
* (except for those which are delivered directly to the guest) --
* there are no exceptions for which we fall through directly to
* the normal host handler.
*
* 32-bit host
* Expected inputs (normal exceptions):
* SCRATCH0 = saved r10
* r10 = thread struct
* r11 = appropriate SRR1 variant (currently used as scratch)
* r13 = saved CR
* *(r10 + THREAD_NORMSAVE(0)) = saved r11
* *(r10 + THREAD_NORMSAVE(2)) = saved r13
*
* Expected inputs (crit/mcheck/debug exceptions):
* appropriate SCRATCH = saved r8
* r8 = exception level stack frame
* r9 = *(r8 + _CCR) = saved CR
* r11 = appropriate SRR1 variant (currently used as scratch)
* *(r8 + GPR9) = saved r9
* *(r8 + GPR10) = saved r10 (r10 not yet clobbered)
* *(r8 + GPR11) = saved r11
*
* 64-bit host
powerpc/booke64: Use SPRG7 for VDSO Previously SPRG3 was marked for use by both VDSO and critical interrupts (though critical interrupts were not fully implemented). In commit 8b64a9dfb091f1eca8b7e58da82f1e7d1d5fe0ad ("powerpc/booke64: Use SPRG0/3 scratch for bolted TLB miss & crit int"), Mihai Caraman made an attempt to resolve this conflict by restoring the VDSO value early in the critical interrupt, but this has some issues: - It's incompatible with EXCEPTION_COMMON which restores r13 from the by-then-overwritten scratch (this cost me some debugging time). - It forces critical exceptions to be a special case handled differently from even machine check and debug level exceptions. - It didn't occur to me that it was possible to make this work at all (by doing a final "ld r13, PACA_EXCRIT+EX_R13(r13)") until after I made (most of) this patch. :-) It might be worth investigating using a load rather than SPRG on return from all exceptions (except TLB misses where the scratch never leaves the SPRG) -- it could save a few cycles. Until then, let's stick with SPRG for all exceptions. Since we cannot use SPRG4-7 for scratch without corrupting the state of a KVM guest, move VDSO to SPRG7 on book3e. Since neither SPRG4-7 nor critical interrupts exist on book3s, SPRG3 is still used for VDSO there. Signed-off-by: Scott Wood <scottwood@freescale.com> Cc: Mihai Caraman <mihai.caraman@freescale.com> Cc: Anton Blanchard <anton@samba.org> Cc: Paul Mackerras <paulus@samba.org> Cc: kvm-ppc@vger.kernel.org
2014-03-11 06:29:38 +08:00
* Expected inputs (GEN/GDBELL/DBG/CRIT/MC exception types):
* r10 = saved CR
* r13 = PACA_POINTER
* *(r13 + PACA_EX##type + EX_R10) = saved r10
* *(r13 + PACA_EX##type + EX_R11) = saved r11
* SPRN_SPRG_##type##_SCRATCH = saved r13
*
* Expected inputs (TLB exception type):
* r10 = saved CR
* r13 = PACA_POINTER
* *(r13 + PACA_EX##type + EX_TLB_R10) = saved r10
* *(r13 + PACA_EX##type + EX_TLB_R11) = saved r11
* SPRN_SPRG_GEN_SCRATCH = saved r13
*
* Only the bolted version of TLB miss exception handlers is supported now.
*/
.macro DO_KVM intno srr1
#ifdef CONFIG_KVM_BOOKE_HV
BEGIN_FTR_SECTION
mtocrf 0x80, r11 /* check MSR[GS] without clobbering reg */
bf 3, 1975f
b kvmppc_handler_\intno\()_\srr1
1975:
END_FTR_SECTION_IFSET(CPU_FTR_EMB_HV)
#endif
.endm
#endif /*__ASSEMBLY__ */
#endif /* ASM_KVM_BOOKE_HV_ASM_H */