[PATCH v5 2/3] KVM: PPC: Book3S HV: Add support for H_RPT_INVALIDATE
David Gibson
david at gibson.dropbear.id.au
Thu Mar 4 17:56:26 AEDT 2021
On Tue, Mar 02, 2021 at 10:28:53AM +0530, Bharata B Rao wrote:
> On Tue, Mar 02, 2021 at 12:45:18PM +1100, David Gibson wrote:
> > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
> > > index 45fd862ac128..38ce3f21b21f 100644
> > > --- a/Documentation/virt/kvm/api.rst
> > > +++ b/Documentation/virt/kvm/api.rst
> > > @@ -6225,6 +6225,24 @@ KVM_RUN_BUS_LOCK flag is used to distinguish between them.
> > > This capability can be used to check / enable 2nd DAWR feature provided
> > > by POWER10 processor.
> > >
> > > +7.23 KVM_CAP_PPC_RPT_INVALIDATE
> > > +------------------------------
> > > +
> > > +:Capability: KVM_CAP_PPC_RPT_INVALIDATE
> > > +:Architectures: ppc
> > > +:Type: vm
> > > +
> > > +This capability indicates that the kernel is capable of handling
> > > +H_RPT_INVALIDATE hcall.
> > > +
> > > +In order to enable the use of H_RPT_INVALIDATE in the guest,
> > > +user space might have to advertise it for the guest. For example,
> > > +IBM pSeries (sPAPR) guest starts using it if "hcall-rpt-invalidate" is
> > > +present in the "ibm,hypertas-functions" device-tree property.
> > > +
> > > +This capability is enabled for hypervisors on platforms like POWER9
> > > +that support radix MMU.
> >
> > Does this mean that KVM will handle the hypercall, even if not
> > explicitly enabled by userspace (qemu)? That's generally not what we
> > want, since we need to allow qemu to set up backwards compatible
> > guests.
>
> This capability only indicates that hypervisor supports the hcall.
>
> QEMU will check for this and conditionally enable the hcall
> (via KVM_CAP_PPC_ENABLE_HCALL ioctl). Enabling the hcall is
> conditional to cap-rpt-invalidate sPAPR machine capability being
> enabled by the user. Will post a followup QEMU patch shortly.
Ok.
> Older QEMU patch can be found here:
> https://lists.gnu.org/archive/html/qemu-devel/2021-01/msg00627.html
>
> >
> > > +
> > > 8. Other capabilities.
> > > ======================
> > >
> > > diff --git a/arch/powerpc/include/asm/book3s/64/tlbflush-radix.h b/arch/powerpc/include/asm/book3s/64/tlbflush-radix.h
> > > index 8b33601cdb9d..a46fd37ad552 100644
> > > --- a/arch/powerpc/include/asm/book3s/64/tlbflush-radix.h
> > > +++ b/arch/powerpc/include/asm/book3s/64/tlbflush-radix.h
> > > @@ -4,6 +4,10 @@
> > >
> > > #include <asm/hvcall.h>
> > >
> > > +#define RIC_FLUSH_TLB 0
> > > +#define RIC_FLUSH_PWC 1
> > > +#define RIC_FLUSH_ALL 2
> > > +
> > > struct vm_area_struct;
> > > struct mm_struct;
> > > struct mmu_gather;
> > > diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h
> > > index 2f5f919f6cd3..a1515f94400e 100644
> > > --- a/arch/powerpc/include/asm/kvm_book3s.h
> > > +++ b/arch/powerpc/include/asm/kvm_book3s.h
> > > @@ -305,6 +305,9 @@ void kvmhv_set_ptbl_entry(unsigned int lpid, u64 dw0, u64 dw1);
> > > void kvmhv_release_all_nested(struct kvm *kvm);
> > > long kvmhv_enter_nested_guest(struct kvm_vcpu *vcpu);
> > > long kvmhv_do_nested_tlbie(struct kvm_vcpu *vcpu);
> > > +long kvmhv_h_rpti_nested(struct kvm_vcpu *vcpu, unsigned long lpid,
> > > + unsigned long type, unsigned long pg_sizes,
> > > + unsigned long start, unsigned long end);
> > > int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu,
> > > u64 time_limit, unsigned long lpcr);
> > > void kvmhv_save_hv_regs(struct kvm_vcpu *vcpu, struct hv_guest_state *hr);
> > > diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
> > > index 652ce85f9410..820caf4e01b7 100644
> > > --- a/arch/powerpc/include/asm/mmu_context.h
> > > +++ b/arch/powerpc/include/asm/mmu_context.h
> > > @@ -124,8 +124,19 @@ static inline bool need_extra_context(struct mm_struct *mm, unsigned long ea)
> > >
> > > #if defined(CONFIG_KVM_BOOK3S_HV_POSSIBLE) && defined(CONFIG_PPC_RADIX_MMU)
> > > extern void radix_kvm_prefetch_workaround(struct mm_struct *mm);
> > > +void do_h_rpt_invalidate(unsigned long pid, unsigned long lpid,
> > > + unsigned long type, unsigned long page_size,
> > > + unsigned long psize, unsigned long start,
> > > + unsigned long end);
> > > #else
> > > static inline void radix_kvm_prefetch_workaround(struct mm_struct *mm) { }
> > > +static inline void do_h_rpt_invalidate(unsigned long pid,
> > > + unsigned long lpid,
> > > + unsigned long type,
> > > + unsigned long page_size,
> > > + unsigned long psize,
> > > + unsigned long start,
> > > + unsigned long end) { }
> > > #endif
> > >
> > > extern void switch_cop(struct mm_struct *next);
> > > diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> > > index 13bad6bf4c95..d83f006fc19d 100644
> > > --- a/arch/powerpc/kvm/book3s_hv.c
> > > +++ b/arch/powerpc/kvm/book3s_hv.c
> > > @@ -921,6 +921,69 @@ static int kvmppc_get_yield_count(struct kvm_vcpu *vcpu)
> > > return yield_count;
> > > }
> > >
> > > +static void do_h_rpt_invalidate_prs(unsigned long pid, unsigned long lpid,
> > > + unsigned long type, unsigned long pg_sizes,
> > > + unsigned long start, unsigned long end)
> > > +{
> > > + unsigned long psize;
> > > + struct mmu_psize_def *def;
> > > +
> > > + for (psize = 0; psize < MMU_PAGE_COUNT; psize++) {
> > > + def = &mmu_psize_defs[psize];
> > > + if (pg_sizes & def->h_rpt_pgsize)
> > > + do_h_rpt_invalidate(pid, lpid, type,
> > > + (1UL << def->shift), psize,
> > > + start, end);
> > > + }
> > > +}
> > > +
> > > +static void kvmppc_nested_rpt_invalidate(struct kvm_vcpu *vcpu)
> > > +{
> > > + do_h_rpt_invalidate_prs(kvmppc_get_gpr(vcpu, 4),
> > > + vcpu->arch.nested->shadow_lpid,
> > > + kvmppc_get_gpr(vcpu, 5),
> > > + kvmppc_get_gpr(vcpu, 6),
> > > + kvmppc_get_gpr(vcpu, 7),
> > > + kvmppc_get_gpr(vcpu, 8));
> > > + kvmppc_set_gpr(vcpu, 3, H_SUCCESS);
> > > +}
> > > +
> > > +static long kvmppc_h_rpt_invalidate(struct kvm_vcpu *vcpu,
> > > + unsigned long pid, unsigned long target,
> > > + unsigned long type, unsigned long pg_sizes,
> > > + unsigned long start, unsigned long end)
> > > +{
> > > + if (!kvm_is_radix(vcpu->kvm))
> > > + return H_UNSUPPORTED;
> > > +
> > > + /*
> > > + * For nested guests, this hcall is handled in
> > > + * L0. See kvmppc_handle_nested_exit() for details.
> > > + */
> > > + if (kvmhv_on_pseries())
> > > + return H_UNSUPPORTED;
> > > +
> > > + if (end < start)
> > > + return H_P5;
> > > +
> > > + if (type & H_RPTI_TYPE_NESTED) {
> > > + if (!nesting_enabled(vcpu->kvm))
> > > + return H_FUNCTION;
> > > +
> > > + /* Support only cores as target */
> > > + if (target != H_RPTI_TARGET_CMMU)
> > > + return H_P2;
> > > +
> >
> > IIUC, we'll hit this code path if an L1 calls this on behalf of an L2,
>
> Correct.
>
> > whereas we'll hit the nested exit code path going straight to
> > kvmhv_h_rpti_nested() if an L2 calls it on behalf of an L3. Is that
> > right?
>
> We will hit the nested exit code path when L2 calls it on behalf
> of L3. Looks like I am not handling this case (hcall issued by
> L2 on behalf of L3 for handling partition scoped translations)
> in the nested exit path.
>
> >
> > > + return kvmhv_h_rpti_nested(vcpu, pid,
> > > + (type & ~H_RPTI_TYPE_NESTED),
> > > + pg_sizes, start, end);
> > > + }
> > > +
> > > + do_h_rpt_invalidate_prs(pid, vcpu->kvm->arch.lpid, type, pg_sizes,
> > > + start, end);
> > > + return H_SUCCESS;
> > > +}
> > > +
> > > int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu)
> > > {
> > > unsigned long req = kvmppc_get_gpr(vcpu, 3);
> > > @@ -1129,6 +1192,14 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu)
> > > */
> > > ret = kvmppc_h_svm_init_abort(vcpu->kvm);
> > > break;
> > > + case H_RPT_INVALIDATE:
> > > + ret = kvmppc_h_rpt_invalidate(vcpu, kvmppc_get_gpr(vcpu, 4),
> > > + kvmppc_get_gpr(vcpu, 5),
> > > + kvmppc_get_gpr(vcpu, 6),
> > > + kvmppc_get_gpr(vcpu, 7),
> > > + kvmppc_get_gpr(vcpu, 8),
> > > + kvmppc_get_gpr(vcpu, 9));
> > > + break;
> > >
> > > default:
> > > return RESUME_HOST;
> > > @@ -1175,6 +1246,7 @@ static int kvmppc_hcall_impl_hv(unsigned long cmd)
> > > case H_XIRR_X:
> > > #endif
> > > case H_PAGE_INIT:
> > > + case H_RPT_INVALIDATE:
> > > return 1;
> > > }
> > >
> > > @@ -1590,6 +1662,24 @@ static int kvmppc_handle_nested_exit(struct kvm_vcpu *vcpu)
> > > if (!xics_on_xive())
> > > kvmppc_xics_rm_complete(vcpu, 0);
> > > break;
> > > + case BOOK3S_INTERRUPT_SYSCALL:
> > > + {
> > > + unsigned long req = kvmppc_get_gpr(vcpu, 3);
> > > +
> > > + /*
> > > + * The H_RPT_INVALIDATE hcalls issued by nested
> > > + * guests for process scoped invalidations when
> > > + * GTSE=0, are handled here in L0.
> > > + */
> >
> > What if the L2 is not calling this for the GTSE=0 case, but on behalf
> > of an L3?
>
> That case would be for flushing partition scoped translations. I am
> realizing that I am not handling that case, but it should be handled
> here in the nested hcall exit path.
>
> Currently I am handling only the hcall requests for process scoped
> translations from nested guests here.
Ok. At the very least you need to detect and fail for that case.
> >
> > > + if (req == H_RPT_INVALIDATE) {
> > > + kvmppc_nested_rpt_invalidate(vcpu);
> > > + r = RESUME_GUEST;
> > > + break;
> > > + }
> > > +
> > > + r = RESUME_HOST;
> > > + break;
> > > + }
> > > default:
> > > r = RESUME_HOST;
> > > break;
> > > diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book3s_hv_nested.c
> > > index 0cd0e7aad588..ca43b2d38dce 100644
> > > --- a/arch/powerpc/kvm/book3s_hv_nested.c
> > > +++ b/arch/powerpc/kvm/book3s_hv_nested.c
> > > @@ -1191,6 +1191,83 @@ long kvmhv_do_nested_tlbie(struct kvm_vcpu *vcpu)
> > > return H_SUCCESS;
> > > }
> > >
> > > +static long do_tlb_invalidate_nested_tlb(struct kvm_vcpu *vcpu,
> > > + unsigned long lpid,
> > > + unsigned long page_size,
> > > + unsigned long ap,
> > > + unsigned long start,
> > > + unsigned long end)
> > > +{
> > > + unsigned long addr = start;
> > > + int ret;
> > > +
> > > + do {
> > > + ret = kvmhv_emulate_tlbie_tlb_addr(vcpu, lpid, ap,
> > > + get_epn(addr));
> > > + if (ret)
> > > + return ret;
> > > + addr += page_size;
> > > + } while (addr < end);
> > > +
> > > + return ret;
> > > +}
> > > +
> > > +static long do_tlb_invalidate_nested_all(struct kvm_vcpu *vcpu,
> > > + unsigned long lpid)
> > > +{
> > > + struct kvm *kvm = vcpu->kvm;
> > > + struct kvm_nested_guest *gp;
> > > +
> > > + gp = kvmhv_get_nested(kvm, lpid, false);
> > > + if (gp) {
> > > + kvmhv_emulate_tlbie_lpid(vcpu, gp, RIC_FLUSH_ALL);
> > > + kvmhv_put_nested(gp);
> > > + }
> > > + return H_SUCCESS;
> > > +}
> > > +
> > > +long kvmhv_h_rpti_nested(struct kvm_vcpu *vcpu, unsigned long lpid,
> > > + unsigned long type, unsigned long pg_sizes,
> > > + unsigned long start, unsigned long end)
> > > +{
> > > + struct kvm_nested_guest *gp;
> > > + long ret;
> > > + unsigned long psize, ap;
> > > +
> > > + /*
> > > + * If L2 lpid isn't valid, we need to return H_PARAMETER.
> > > + *
> > > + * However, nested KVM issues a L2 lpid flush call when creating
> > > + * partition table entries for L2. This happens even before the
> > > + * corresponding shadow lpid is created in HV which happens in
> > > + * H_ENTER_NESTED call. Since we can't differentiate this case from
> > > + * the invalid case, we ignore such flush requests and return success.
> > > + */
> >
> > What if this is being called on behalf of an L3 or deeper? Do we need
> > something to do a translation from L3 to L2 addresses?
>
> I am not sure, I will have to check if gp->shadow_lpid points to
> correct nested LPID in all the cases.
>
> >
> > > + gp = kvmhv_find_nested(vcpu->kvm, lpid);
> > > + if (!gp)
> > > + return H_SUCCESS;
>
> Regards,
> Bharata.
>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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