On Wed, Feb 28, 2018 at 01:52:26AM +0800, wei.guo.simon@xxxxxxxxx wrote: > From: Simon Guo <wei.guo.simon@xxxxxxxxx> > > Currently kernel doesn't use transaction memory. > And there is an issue for privilege guest that: > tbegin/tsuspend/tresume/tabort TM instructions can impact MSR TM bits > without trap into PR host. So following code will lead to a false mfmsr > result: > tbegin <- MSR bits update to Transaction active. > beq <- failover handler branch > mfmsr <- still read MSR bits from magic page with > transaction inactive. > > It is not an issue for non-privilege guest since its mfmsr is not patched > with magic page and will always trap into PR host. > > This patch will always fail tbegin attempt for privilege guest, so that > the above issue is prevented. It is benign since currently (guest) kernel > doesn't initiate a transaction. > > Test case: > https://github.com/justdoitqd/publicFiles/blob/master/test_tbegin_pr.c > > Signed-off-by: Simon Guo <wei.guo.simon@xxxxxxxxx> > --- > arch/powerpc/include/asm/kvm_book3s.h | 2 ++ > arch/powerpc/kvm/book3s_emulate.c | 43 +++++++++++++++++++++++++++++++++++ > arch/powerpc/kvm/book3s_pr.c | 11 ++++++++- > 3 files changed, 55 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h > index 2ecb6a3..9690280 100644 > --- a/arch/powerpc/include/asm/kvm_book3s.h > +++ b/arch/powerpc/include/asm/kvm_book3s.h > @@ -258,9 +258,11 @@ extern void kvmppc_copy_from_svcpu(struct kvm_vcpu *vcpu, > #ifdef CONFIG_PPC_TRANSACTIONAL_MEM > void kvmppc_save_tm_pr(struct kvm_vcpu *vcpu); > void kvmppc_restore_tm_pr(struct kvm_vcpu *vcpu); > +void kvmppc_restore_tm_sprs(struct kvm_vcpu *vcpu); > #else > static inline void kvmppc_save_tm_pr(struct kvm_vcpu *vcpu) {} > static inline void kvmppc_restore_tm_pr(struct kvm_vcpu *vcpu) {} > +static inline void kvmppc_restore_tm_sprs(struct kvm_vcpu *vcpu) {} > #endif > > extern int kvm_irq_bypass; > diff --git a/arch/powerpc/kvm/book3s_emulate.c b/arch/powerpc/kvm/book3s_emulate.c > index a03533d..90b5f59 100644 > --- a/arch/powerpc/kvm/book3s_emulate.c > +++ b/arch/powerpc/kvm/book3s_emulate.c > @@ -23,6 +23,7 @@ > #include <asm/reg.h> > #include <asm/switch_to.h> > #include <asm/time.h> > +#include <asm/tm.h> > #include "book3s.h" > > #define OP_19_XOP_RFID 18 > @@ -47,6 +48,8 @@ > #define OP_31_XOP_EIOIO 854 > #define OP_31_XOP_SLBMFEE 915 > > +#define OP_31_XOP_TBEGIN 654 > + > /* DCBZ is actually 1014, but we patch it to 1010 so we get a trap */ > #define OP_31_XOP_DCBZ 1010 > > @@ -362,6 +365,46 @@ int kvmppc_core_emulate_op_pr(struct kvm_run *run, struct kvm_vcpu *vcpu, > > break; > } > +#ifdef CONFIG_PPC_TRANSACTIONAL_MEM > + case OP_31_XOP_TBEGIN: > + { > + if (!cpu_has_feature(CPU_FTR_TM)) > + break; > + > + if (!(kvmppc_get_msr(vcpu) & MSR_TM)) { > + kvmppc_trigger_fac_interrupt(vcpu, FSCR_TM_LG); > + emulated = EMULATE_AGAIN; > + break; > + } > + > + if (!(kvmppc_get_msr(vcpu) & MSR_PR)) { > + preempt_disable(); > + vcpu->arch.cr = (CR0_TBEGIN_FAILURE | > + (vcpu->arch.cr & ~(CR0_MASK << CR0_SHIFT))); > + > + vcpu->arch.texasr = (TEXASR_FS | TEXASR_EX | > + (((u64)(TM_CAUSE_EMULATE | TM_CAUSE_PERSISTENT)) > + << TEXASR_FC_LG)); > + > + if ((inst >> 21) & 0x1) > + vcpu->arch.texasr |= TEXASR_ROT; > + > + if (kvmppc_get_msr(vcpu) & MSR_PR) > + vcpu->arch.texasr |= TEXASR_PR; This if statement seems unnecessary, since we only get here when MSR_PR is clear. Paul.
