Nicholas Piggin <npiggin@xxxxxxxxx> writes: > Move the GUEST_MODE_SKIP logic into KVM code. This is quite a KVM > internal detail that has no real need to be in common handlers. > > Also add a comment explaining why this this thing exists. this this > > Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx> Reviewed-by: Fabiano Rosas <farosas@xxxxxxxxxxxxx> > --- > arch/powerpc/kernel/exceptions-64s.S | 60 -------------------------- > arch/powerpc/kvm/book3s_64_entry.S | 64 ++++++++++++++++++++++++---- > 2 files changed, 56 insertions(+), 68 deletions(-) > > diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S > index a1640d6ea65d..96f22c582213 100644 > --- a/arch/powerpc/kernel/exceptions-64s.S > +++ b/arch/powerpc/kernel/exceptions-64s.S > @@ -133,7 +133,6 @@ name: > #define IBRANCH_TO_COMMON .L_IBRANCH_TO_COMMON_\name\() /* ENTRY branch to common */ > #define IREALMODE_COMMON .L_IREALMODE_COMMON_\name\() /* Common runs in realmode */ > #define IMASK .L_IMASK_\name\() /* IRQ soft-mask bit */ > -#define IKVM_SKIP .L_IKVM_SKIP_\name\() /* Generate KVM skip handler */ > #define IKVM_REAL .L_IKVM_REAL_\name\() /* Real entry tests KVM */ > #define __IKVM_REAL(name) .L_IKVM_REAL_ ## name > #define IKVM_VIRT .L_IKVM_VIRT_\name\() /* Virt entry tests KVM */ > @@ -191,9 +190,6 @@ do_define_int n > .ifndef IMASK > IMASK=0 > .endif > - .ifndef IKVM_SKIP > - IKVM_SKIP=0 > - .endif > .ifndef IKVM_REAL > IKVM_REAL=0 > .endif > @@ -254,15 +250,10 @@ do_define_int n > .balign IFETCH_ALIGN_BYTES > \name\()_kvm: > > - .if IKVM_SKIP > - cmpwi r10,KVM_GUEST_MODE_SKIP > - beq 89f > - .else > BEGIN_FTR_SECTION > ld r10,IAREA+EX_CFAR(r13) > std r10,HSTATE_CFAR(r13) > END_FTR_SECTION_IFSET(CPU_FTR_CFAR) > - .endif > > ld r10,IAREA+EX_CTR(r13) > mtctr r10 > @@ -289,27 +280,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR) > ori r12,r12,(IVEC) > .endif > b kvmppc_interrupt > - > - .if IKVM_SKIP > -89: mtocrf 0x80,r9 > - ld r10,IAREA+EX_CTR(r13) > - mtctr r10 > - ld r9,IAREA+EX_R9(r13) > - ld r10,IAREA+EX_R10(r13) > - ld r11,IAREA+EX_R11(r13) > - ld r12,IAREA+EX_R12(r13) > - .if IHSRR_IF_HVMODE > - BEGIN_FTR_SECTION > - b kvmppc_skip_Hinterrupt > - FTR_SECTION_ELSE > - b kvmppc_skip_interrupt > - ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206) > - .elseif IHSRR > - b kvmppc_skip_Hinterrupt > - .else > - b kvmppc_skip_interrupt > - .endif > - .endif > .endm > > #else > @@ -1128,7 +1098,6 @@ INT_DEFINE_BEGIN(machine_check) > ISET_RI=0 > IDAR=1 > IDSISR=1 > - IKVM_SKIP=1 > IKVM_REAL=1 > INT_DEFINE_END(machine_check) > > @@ -1419,7 +1388,6 @@ INT_DEFINE_BEGIN(data_access) > IVEC=0x300 > IDAR=1 > IDSISR=1 > - IKVM_SKIP=1 > IKVM_REAL=1 > INT_DEFINE_END(data_access) > > @@ -1465,7 +1433,6 @@ INT_DEFINE_BEGIN(data_access_slb) > IVEC=0x380 > IRECONCILE=0 > IDAR=1 > - IKVM_SKIP=1 > IKVM_REAL=1 > INT_DEFINE_END(data_access_slb) > > @@ -2111,7 +2078,6 @@ INT_DEFINE_BEGIN(h_data_storage) > IHSRR=1 > IDAR=1 > IDSISR=1 > - IKVM_SKIP=1 > IKVM_REAL=1 > IKVM_VIRT=1 > INT_DEFINE_END(h_data_storage) > @@ -3088,32 +3054,6 @@ EXPORT_SYMBOL(do_uaccess_flush) > MASKED_INTERRUPT > MASKED_INTERRUPT hsrr=1 > > -#ifdef CONFIG_KVM_BOOK3S_64_HANDLER > -kvmppc_skip_interrupt: > - /* > - * Here all GPRs are unchanged from when the interrupt happened > - * except for r13, which is saved in SPRG_SCRATCH0. > - */ > - mfspr r13, SPRN_SRR0 > - addi r13, r13, 4 > - mtspr SPRN_SRR0, r13 > - GET_SCRATCH0(r13) > - RFI_TO_KERNEL > - b . > - > -kvmppc_skip_Hinterrupt: > - /* > - * Here all GPRs are unchanged from when the interrupt happened > - * except for r13, which is saved in SPRG_SCRATCH0. > - */ > - mfspr r13, SPRN_HSRR0 > - addi r13, r13, 4 > - mtspr SPRN_HSRR0, r13 > - GET_SCRATCH0(r13) > - HRFI_TO_KERNEL > - b . > -#endif > - > /* > * Relocation-on interrupts: A subset of the interrupts can be delivered > * with IR=1/DR=1, if AIL==2 and MSR.HV won't be changed by delivering > diff --git a/arch/powerpc/kvm/book3s_64_entry.S b/arch/powerpc/kvm/book3s_64_entry.S > index 147ebf1c3c1f..820d103e5f50 100644 > --- a/arch/powerpc/kvm/book3s_64_entry.S > +++ b/arch/powerpc/kvm/book3s_64_entry.S > @@ -1,9 +1,10 @@ > +#include <asm/asm-offsets.h> > #include <asm/cache.h> > -#include <asm/ppc_asm.h> > +#include <asm/exception-64s.h> > #include <asm/kvm_asm.h> > -#include <asm/reg.h> > -#include <asm/asm-offsets.h> > #include <asm/kvm_book3s_asm.h> > +#include <asm/ppc_asm.h> > +#include <asm/reg.h> > > /* > * This is branched to from interrupt handlers in exception-64s.S which set > @@ -19,17 +20,64 @@ kvmppc_interrupt: > * guest R12 saved in shadow VCPU SCRATCH0 > * guest R13 saved in SPRN_SCRATCH0 > */ > + std r9,HSTATE_SCRATCH2(r13) > + lbz r9,HSTATE_IN_GUEST(r13) > + cmpwi r9,KVM_GUEST_MODE_SKIP > + beq- .Lmaybe_skip > +.Lno_skip: > #ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE > - std r9, HSTATE_SCRATCH2(r13) > - lbz r9, HSTATE_IN_GUEST(r13) > - cmpwi r9, KVM_GUEST_MODE_HOST_HV > + 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_SCRATCH2(r13) > + cmpwi r9,KVM_GUEST_MODE_GUEST > + ld r9,HSTATE_SCRATCH2(r13) > beq kvmppc_interrupt_pr > #endif > b kvmppc_interrupt_hv > #else > b kvmppc_interrupt_pr > #endif > + > +/* > + * KVM uses a trick where it is running in MSR[HV]=1 mode in real-mode with the > + * guest MMU context loaded, and it sets KVM_GUEST_MODE_SKIP and enables > + * MSR[DR]=1 while leaving MSR[IR]=0, so it continues to fetch HV instructions > + * but loads and stores will access the guest context. This is used to load > + * the faulting instruction without walking page tables. > + * > + * However the guest context may not be able to translate, or it may cause a > + * machine check or other issue, which will result in a fault in the host > + * (even with KVM-HV). > + * > + * These faults are caught here and if the fault was (or was likely) due to > + * that load, then we just return with the PC advanced +4 and skip the load, > + * which then goes via the slow path. > + */ > +.Lmaybe_skip: > + cmpwi r12,BOOK3S_INTERRUPT_MACHINE_CHECK > + beq 1f > + cmpwi r12,BOOK3S_INTERRUPT_DATA_STORAGE > + beq 1f > + cmpwi r12,BOOK3S_INTERRUPT_DATA_SEGMENT > + beq 1f > +#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE > + cmpwi r12,BOOK3S_INTERRUPT_H_DATA_STORAGE | 0x2 > + beq 2f > +#endif > + b .Lno_skip > +1: mfspr r9,SPRN_SRR0 > + addi r9,r9,4 > + mtspr SPRN_SRR0,r9 > + ld r12,HSTATE_SCRATCH0(r13) > + ld r9,HSTATE_SCRATCH2(r13) > + GET_SCRATCH0(r13) > + RFI_TO_KERNEL > +#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE > +2: mfspr r9,SPRN_HSRR0 > + addi r9,r9,4 > + mtspr SPRN_HSRR0,r9 > + ld r12,HSTATE_SCRATCH0(r13) > + ld r9,HSTATE_SCRATCH2(r13) > + GET_SCRATCH0(r13) > + HRFI_TO_KERNEL > +#endif
