| Message ID | ZAgs25dCmLrVkBdU@cleo (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | powerpc/kvm: Enable HV KVM guests to use prefixed instructions to access emulated MMIO | expand |
> On 08-Mar-2023, at 12:06 PM, Paul Mackerras <paulus@ozlabs.org> wrote: > > Now that we can read prefixed instructions from a HV KVM guest and > emulate prefixed load/store instructions to emulated MMIO locations, > we can add HFSCR_PREFIXED into the set of bits that are set in the > HFSCR for a HV KVM guest on POWER10, allowing the guest to use > prefixed instructions. > > PR KVM has not yet been extended to handle prefixed instructions in > all situations where we might need to emulate them, so prevent the > guest from enabling prefixed instructions in the FSCR for now. > > Reviewed-by: Nicholas Piggin <npiggin@gmail.com> > Tested-by: Nicholas Piggin <npiggin@gmail.com> > Signed-off-by: Paul Mackerras <paulus@ozlabs.org> > --- Tested on a Power10 system. Prefixed instructions work correctly. Tested-by: Sachin Sant <sachinp@linux.ibm.com> > arch/powerpc/include/asm/reg.h | 1 + > arch/powerpc/kvm/book3s_hv.c | 9 +++++++-- > arch/powerpc/kvm/book3s_pr.c | 2 ++ > arch/powerpc/kvm/book3s_rmhandlers.S | 1 + > 4 files changed, 11 insertions(+), 2 deletions(-) >
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h index 1e8b2e04e626..7434a3300d84 100644 --- a/arch/powerpc/include/asm/reg.h +++ b/arch/powerpc/include/asm/reg.h @@ -417,6 +417,7 @@ #define FSCR_DSCR __MASK(FSCR_DSCR_LG) #define FSCR_INTR_CAUSE (ASM_CONST(0xFF) << 56) /* interrupt cause */ #define SPRN_HFSCR 0xbe /* HV=1 Facility Status & Control Register */ +#define HFSCR_PREFIX __MASK(FSCR_PREFIX_LG) #define HFSCR_MSGP __MASK(FSCR_MSGP_LG) #define HFSCR_TAR __MASK(FSCR_TAR_LG) #define HFSCR_EBB __MASK(FSCR_EBB_LG) diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 0d17f4443021..c5b24ab90fb2 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -2921,13 +2921,18 @@ static int kvmppc_core_vcpu_create_hv(struct kvm_vcpu *vcpu) /* * Set the default HFSCR for the guest from the host value. - * This value is only used on POWER9. - * On POWER9, we want to virtualize the doorbell facility, so we + * This value is only used on POWER9 and later. + * On >= POWER9, we want to virtualize the doorbell facility, so we * don't set the HFSCR_MSGP bit, and that causes those instructions * to trap and then we emulate them. */ vcpu->arch.hfscr = HFSCR_TAR | HFSCR_EBB | HFSCR_PM | HFSCR_BHRB | HFSCR_DSCR | HFSCR_VECVSX | HFSCR_FP; + + /* On POWER10 and later, allow prefixed instructions */ + if (cpu_has_feature(CPU_FTR_ARCH_31)) + vcpu->arch.hfscr |= HFSCR_PREFIX; + if (cpu_has_feature(CPU_FTR_HVMODE)) { vcpu->arch.hfscr &= mfspr(SPRN_HFSCR); #ifdef CONFIG_PPC_TRANSACTIONAL_MEM diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c index 940ab010a471..fa010d92a8d2 100644 --- a/arch/powerpc/kvm/book3s_pr.c +++ b/arch/powerpc/kvm/book3s_pr.c @@ -1044,6 +1044,8 @@ void kvmppc_set_fscr(struct kvm_vcpu *vcpu, u64 fscr) { if (fscr & FSCR_SCV) fscr &= ~FSCR_SCV; /* SCV must not be enabled */ + /* Prohibit prefixed instructions for now */ + fscr &= ~FSCR_PREFIX; if ((vcpu->arch.fscr & FSCR_TAR) && !(fscr & FSCR_TAR)) { /* TAR got dropped, drop it in shadow too */ kvmppc_giveup_fac(vcpu, FSCR_TAR_LG); diff --git a/arch/powerpc/kvm/book3s_rmhandlers.S b/arch/powerpc/kvm/book3s_rmhandlers.S index 03886ca24498..0a557ffca9fe 100644 --- a/arch/powerpc/kvm/book3s_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_rmhandlers.S @@ -123,6 +123,7 @@ INTERRUPT_TRAMPOLINE BOOK3S_INTERRUPT_ALTIVEC kvmppc_handler_skip_ins: /* Patch the IP to the next instruction */ + /* Note that prefixed instructions are disabled in PR KVM for now */ mfsrr0 r12 addi r12, r12, 4 mtsrr0 r12