Hi David, I know it's been a while since you posted this patchset, but thought you might appreciate the feedback anyway. Some of my comments/suggestions relate to portability with MIPS32. I don't object if you respond to those by just adding "depends on 64BIT" so that I & others can fix it up in subsequent patches. On 08/06/13 00:03, David Daney wrote: > From: David Daney <david.daney@xxxxxxxxxx> > > Currently this is a little complex, here are the facts about how it works: > > o When running in Guest mode we set the high bit of CP0_XCONTEXT. If > this bit is clear, we don't do anything special on an exception. > > o If we are in guest mode, upon an exception we: > > 1) load the stack pointer from the mips_kvm_rootsp array instead of > kernelsp. > > 2) Clear GuestCtl[GM] and high bit of CP0_XCONTEXT. > > 3) Restore host ASID and PGD pointer. > > o Upon restarting from an exception we test the task TIF_GUESTMODE > flag if it is clear, nothing special is done. > > o If Guest mode is active for the thread we: > > 1) Compare the stack pointer to mips_kvm_rootsp, if it doesn't match > we are not reentering guest mode, so no more special processing > is done. > > 2) If reentering guest mode: > > 2a) Set high bit of CP0_XCONTEXT and GuestCtl[GM]. > > 2b) Set Guest mode ASID and PGD pointer. > > This allows a single set of exception handlers to be used for both > host and guest mode operation. > > Signed-off-by: David Daney <david.daney@xxxxxxxxxx> > --- > arch/mips/include/asm/stackframe.h | 135 ++++++++++++++++++++++++++++++++++++- > 1 file changed, 132 insertions(+), 3 deletions(-) > > diff --git a/arch/mips/include/asm/stackframe.h b/arch/mips/include/asm/stackframe.h > index 20627b2..bf2ec48 100644 > --- a/arch/mips/include/asm/stackframe.h > +++ b/arch/mips/include/asm/stackframe.h > @@ -17,6 +17,7 @@ > #include <asm/asmmacro.h> > #include <asm/mipsregs.h> > #include <asm/asm-offsets.h> > +#include <asm/thread_info.h> > > /* > * For SMTC kernel, global IE should be left set, and interrupts > @@ -98,7 +99,9 @@ > #define CPU_ID_REG CP0_CONTEXT > #define CPU_ID_MFC0 MFC0 > #endif > - .macro get_saved_sp /* SMP variation */ > +#define CPU_ID_MASK ((1 << 13) - 1) (I was going to say this could be made more portable by using the lowest bit of PTEBASE (i.e. bit PTEBASE_SHIFT) for the guest mode state instead of bit 63, and setting CPU_ID_MASK to -2 to mask off the lowest instead of highest bit, but now I see you test it with bgez... In that case I suppose it makes sense to use bit 31 for 32BIT, which still leaves 6 bits for the processor id - potentially expandable back to 7 by shifting the processor id down a couple of bits and utilising the masking that you've added). > + > + .macro get_saved_sp_for_save_some /* SMP variation */ > CPU_ID_MFC0 k0, CPU_ID_REG I suspect this shouldn't be here since both users of the macro already seem to ensure it's done. > #if defined(CONFIG_32BIT) || defined(KBUILD_64BIT_SYM32) > lui k1, %hi(kernelsp) > @@ -110,15 +113,49 @@ > dsll k1, 16 > #endif > LONG_SRL k0, PTEBASE_SHIFT > +#ifdef CONFIG_KVM_MIPSVZ > + andi k0, CPU_ID_MASK /* high bits indicate guest mode. */ > +#endif > LONG_ADDU k1, k0 > LONG_L k1, %lo(kernelsp)(k1) > .endm > > + .macro get_saved_sp > + CPU_ID_MFC0 k0, CPU_ID_REG > + get_saved_sp_for_save_some > + .endm > + > + .macro get_mips_kvm_rootsp /* SMP variation */ > +#if defined(CONFIG_32BIT) || defined(KBUILD_64BIT_SYM32) > + lui k1, %hi(mips_kvm_rootsp) > +#else > + lui k1, %highest(mips_kvm_rootsp) > + daddiu k1, %higher(mips_kvm_rootsp) > + dsll k1, 16 > + daddiu k1, %hi(mips_kvm_rootsp) > + dsll k1, 16 > +#endif > + LONG_SRL k0, PTEBASE_SHIFT > + andi k0, CPU_ID_MASK /* high bits indicate guest mode. */ > + LONG_ADDU k1, k0 > + LONG_L k1, %lo(mips_kvm_rootsp)(k1) > + .endm > + > .macro set_saved_sp stackp temp temp2 > CPU_ID_MFC0 \temp, CPU_ID_REG > LONG_SRL \temp, PTEBASE_SHIFT > +#ifdef CONFIG_KVM_MIPSVZ > + andi k0, CPU_ID_MASK /* high bits indicate guest mode. */ > +#endif > LONG_S \stackp, kernelsp(\temp) > .endm > + > + .macro set_mips_kvm_rootsp stackp temp > + CPU_ID_MFC0 \temp, CPU_ID_REG > + LONG_SRL \temp, PTEBASE_SHIFT > + andi k0, CPU_ID_MASK /* high bits indicate guest mode. */ Should that be s/k0/\temp/? > + LONG_S \stackp, mips_kvm_rootsp(\temp) > + .endm > #else > .macro get_saved_sp /* Uniprocessor variation */ > #ifdef CONFIG_CPU_JUMP_WORKAROUNDS > @@ -152,9 +189,27 @@ > LONG_L k1, %lo(kernelsp)(k1) > .endm > > + .macro get_mips_kvm_rootsp /* Uniprocessor variation */ > +#if defined(CONFIG_32BIT) || defined(KBUILD_64BIT_SYM32) > + lui k1, %hi(mips_kvm_rootsp) > +#else > + lui k1, %highest(mips_kvm_rootsp) > + daddiu k1, %higher(mips_kvm_rootsp) > + dsll k1, k1, 16 > + daddiu k1, %hi(mips_kvm_rootsp) > + dsll k1, k1, 16 > +#endif > + LONG_L k1, %lo(mips_kvm_rootsp)(k1) > + .endm > + > + > .macro set_saved_sp stackp temp temp2 > LONG_S \stackp, kernelsp > .endm > + > + .macro set_mips_kvm_rootsp stackp temp > + LONG_S \stackp, mips_kvm_rootsp > + .endm > #endif > > .macro SAVE_SOME > @@ -164,11 +219,21 @@ > mfc0 k0, CP0_STATUS > sll k0, 3 /* extract cu0 bit */ > .set noreorder > +#ifdef CONFIG_KVM_MIPSVZ > + bgez k0, 7f brief comments around here would make it easier to follow, e.g. /* from kernel */ ... > + CPU_ID_MFC0 k0, CPU_ID_REG > + bgez k0, 8f /* from userland */ > + move k1, sp /* from guest */ > + get_mips_kvm_rootsp > + b 8f > + nop > +#else > bltz k0, 8f > move k1, sp > +#endif > .set reorder > /* Called from user mode, new stack. */ > - get_saved_sp > +7: get_saved_sp_for_save_some you don't appear to have defined a !CONFIG_SMP version of get_saved_sp_for_save_some? > #ifndef CONFIG_CPU_DADDI_WORKAROUNDS > 8: move k0, sp > PTR_SUBU sp, k1, PT_SIZE > @@ -227,6 +292,35 @@ > LONG_S $31, PT_R31(sp) > ori $28, sp, _THREAD_MASK > xori $28, _THREAD_MASK > +#ifdef CONFIG_KVM_MIPSVZ > + CPU_ID_MFC0 k0, CPU_ID_REG > + .set noreorder > + bgez k0, 8f > + /* Must clear GuestCtl0[GM] */ > + dins k0, zero, 63, 1 Looks like we need a LONG_INS (and friends) defined in asm.h for this > + .set reorder > + dmtc0 k0, CPU_ID_REG Lets define a CPU_ID_MTC0 similar to CPU_ID_MFC0. > + mfc0 k0, CP0_GUESTCTL0 > + ins k0, zero, MIPS_GUESTCTL0B_GM, 1 > + mtc0 k0, CP0_GUESTCTL0 > + LONG_L v0, TI_TASK($28) > + lw v1, THREAD_MM_ASID(v0) > + dmtc0 v1, CP0_ENTRYHI MTC0. > + LONG_L v1, TASK_MM(v0) > + .set noreorder > + jal tlbmiss_handler_setup_pgd_array > + LONG_L a0, MM_PGD(v1) > + .set reorder > + /* > + * With KVM_MIPSVZ, we must not clobber k0/k1 > + * they were saved before they were used > + */ > +8: > + MFC0 k0, CP0_KSCRATCH1 > + MFC0 v1, CP0_KSCRATCH2 > + LONG_S k0, PT_R26(sp) > + LONG_S v1, PT_R27(sp) > +#endif > #ifdef CONFIG_CPU_CAVIUM_OCTEON > .set mips64 > pref 0, 0($28) /* Prefetch the current pointer */ > @@ -439,10 +533,45 @@ > .set mips0 > #endif /* CONFIG_MIPS_MT_SMTC */ > LONG_L v1, PT_EPC(sp) > + LONG_L $25, PT_R25(sp) Is this an optimisation? It's unclear why it's been moved. > MTC0 v1, CP0_EPC > +#ifdef CONFIG_KVM_MIPSVZ > + /* > + * Only if TIF_GUESTMODE && sp is the saved KVM sp, return to > + * guest mode. > + */ > + LONG_L v0, TI_FLAGS($28) > + li k1, _TIF_GUESTMODE > + and v0, v0, k1 > + beqz v0, 8f > + CPU_ID_MFC0 k0, CPU_ID_REG > + get_mips_kvm_rootsp > + PTR_SUBU k1, k1, PT_SIZE > + bne k1, sp, 8f > + /* Set the high order bit of CPU_ID_REG to indicate guest mode. */ > + dli v0, 1 I think li will do here. > + dmfc0 v1, CPU_ID_REG CPU_ID_MFC0 > + dins v1, v0, 63, 1 LONG_INS > + dmtc0 v1, CPU_ID_REG CPU_ID_MTC0 > + /* Must set GuestCtl0[GM] */ > + mfc0 v1, CP0_GUESTCTL0 > + ins v1, v0, MIPS_GUESTCTL0B_GM, 1 > + mtc0 v1, CP0_GUESTCTL0 > + > + LONG_L v0, TI_TASK($28) > + lw v1, THREAD_GUEST_ASID(v0) > + dmtc0 v1, CP0_ENTRYHI MTC0 > + LONG_L v1, THREAD_VCPU(v0) > + LONG_L v1, KVM_VCPU_KVM(v1) > + LONG_L v1, KVM_ARCH_IMPL(v1) > + .set noreorder > + jal tlbmiss_handler_setup_pgd_array > + LONG_L a0, KVM_MIPS_VZ_PGD(v1) > + .set reorder > +8: > +#endif > LONG_L $31, PT_R31(sp) > LONG_L $28, PT_R28(sp) > - LONG_L $25, PT_R25(sp) > #ifdef CONFIG_64BIT > LONG_L $8, PT_R8(sp) > LONG_L $9, PT_R9(sp) > Cheers James
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