| Message ID | 20201124105953.39325-2-ravi.bangoria@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: PPC: Power10 2nd DAWR enablement | expand |
Ravi Bangoria <ravi.bangoria@linux.ibm.com> writes: > On powerpc, L1 hypervisor takes help of L0 using H_ENTER_NESTED > hcall to load L2 guest state in cpu. L1 hypervisor prepares the > L2 state in struct hv_guest_state and passes a pointer to it via > hcall. Using that pointer, L0 reads/writes that state directly > from/to L1 memory. Thus L0 must be aware of hv_guest_state layout > of L1. Currently it uses version field to achieve this. i.e. If > L0 hv_guest_state.version != L1 hv_guest_state.version, L0 won't > allow nested kvm guest. > > This restriction can be loosen up a bit. L0 can be taught to > understand older layout of hv_guest_state, if we restrict the > new member to be added only at the end. i.e. we can allow > nested guest even when L0 hv_guest_state.version > L1 > hv_guest_state.version. Though, the other way around is not > possible. > > Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com> Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com> > --- > arch/powerpc/include/asm/hvcall.h | 17 +++++++-- > arch/powerpc/kvm/book3s_hv_nested.c | 53 ++++++++++++++++++++++++----- > 2 files changed, 59 insertions(+), 11 deletions(-) > > diff --git a/arch/powerpc/include/asm/hvcall.h b/arch/powerpc/include/asm/hvcall.h > index fbb377055471..a7073fddb657 100644 > --- a/arch/powerpc/include/asm/hvcall.h > +++ b/arch/powerpc/include/asm/hvcall.h > @@ -524,9 +524,12 @@ struct h_cpu_char_result { > u64 behaviour; > }; > > -/* Register state for entering a nested guest with H_ENTER_NESTED */ > +/* > + * Register state for entering a nested guest with H_ENTER_NESTED. > + * New member must be added at the end. > + */ > struct hv_guest_state { > - u64 version; /* version of this structure layout */ > + u64 version; /* version of this structure layout, must be first */ > u32 lpid; > u32 vcpu_token; > /* These registers are hypervisor privileged (at least for writing) */ > @@ -560,6 +563,16 @@ struct hv_guest_state { > /* Latest version of hv_guest_state structure */ > #define HV_GUEST_STATE_VERSION 1 > > +static inline int hv_guest_state_size(unsigned int version) > +{ > + switch (version) { > + case 1: > + return offsetofend(struct hv_guest_state, ppr); > + default: > + return -1; > + } > +} > + > #endif /* __ASSEMBLY__ */ > #endif /* __KERNEL__ */ > #endif /* _ASM_POWERPC_HVCALL_H */ > diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book3s_hv_nested.c > index 33b58549a9aa..2b433c3bacea 100644 > --- a/arch/powerpc/kvm/book3s_hv_nested.c > +++ b/arch/powerpc/kvm/book3s_hv_nested.c > @@ -215,6 +215,45 @@ static void kvmhv_nested_mmio_needed(struct kvm_vcpu *vcpu, u64 regs_ptr) > } > } > > +static int kvmhv_read_guest_state_and_regs(struct kvm_vcpu *vcpu, > + struct hv_guest_state *l2_hv, > + struct pt_regs *l2_regs, > + u64 hv_ptr, u64 regs_ptr) > +{ > + int size; > + > + if (kvm_vcpu_read_guest(vcpu, hv_ptr, &(l2_hv->version), > + sizeof(l2_hv->version))) > + return -1; > + > + if (kvmppc_need_byteswap(vcpu)) > + l2_hv->version = swab64(l2_hv->version); > + > + size = hv_guest_state_size(l2_hv->version); > + if (size < 0) > + return -1; > + > + return kvm_vcpu_read_guest(vcpu, hv_ptr, l2_hv, size) || > + kvm_vcpu_read_guest(vcpu, regs_ptr, l2_regs, > + sizeof(struct pt_regs)); > +} > + > +static int kvmhv_write_guest_state_and_regs(struct kvm_vcpu *vcpu, > + struct hv_guest_state *l2_hv, > + struct pt_regs *l2_regs, > + u64 hv_ptr, u64 regs_ptr) > +{ > + int size; > + > + size = hv_guest_state_size(l2_hv->version); > + if (size < 0) > + return -1; > + > + return kvm_vcpu_write_guest(vcpu, hv_ptr, l2_hv, size) || > + kvm_vcpu_write_guest(vcpu, regs_ptr, l2_regs, > + sizeof(struct pt_regs)); > +} > + > long kvmhv_enter_nested_guest(struct kvm_vcpu *vcpu) > { > long int err, r; > @@ -235,17 +274,15 @@ long kvmhv_enter_nested_guest(struct kvm_vcpu *vcpu) > hv_ptr = kvmppc_get_gpr(vcpu, 4); > regs_ptr = kvmppc_get_gpr(vcpu, 5); > vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu); > - err = kvm_vcpu_read_guest(vcpu, hv_ptr, &l2_hv, > - sizeof(struct hv_guest_state)) || > - kvm_vcpu_read_guest(vcpu, regs_ptr, &l2_regs, > - sizeof(struct pt_regs)); > + err = kvmhv_read_guest_state_and_regs(vcpu, &l2_hv, &l2_regs, > + hv_ptr, regs_ptr); > srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx); > if (err) > return H_PARAMETER; > > if (kvmppc_need_byteswap(vcpu)) > byteswap_hv_regs(&l2_hv); > - if (l2_hv.version != HV_GUEST_STATE_VERSION) > + if (l2_hv.version > HV_GUEST_STATE_VERSION) > return H_P2; > > if (kvmppc_need_byteswap(vcpu)) > @@ -325,10 +362,8 @@ long kvmhv_enter_nested_guest(struct kvm_vcpu *vcpu) > byteswap_pt_regs(&l2_regs); > } > vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu); > - err = kvm_vcpu_write_guest(vcpu, hv_ptr, &l2_hv, > - sizeof(struct hv_guest_state)) || > - kvm_vcpu_write_guest(vcpu, regs_ptr, &l2_regs, > - sizeof(struct pt_regs)); > + err = kvmhv_write_guest_state_and_regs(vcpu, &l2_hv, &l2_regs, > + hv_ptr, regs_ptr); > srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx); > if (err) > return H_AUTHORITY;
diff --git a/arch/powerpc/include/asm/hvcall.h b/arch/powerpc/include/asm/hvcall.h index fbb377055471..a7073fddb657 100644 --- a/arch/powerpc/include/asm/hvcall.h +++ b/arch/powerpc/include/asm/hvcall.h @@ -524,9 +524,12 @@ struct h_cpu_char_result { u64 behaviour; }; -/* Register state for entering a nested guest with H_ENTER_NESTED */ +/* + * Register state for entering a nested guest with H_ENTER_NESTED. + * New member must be added at the end. + */ struct hv_guest_state { - u64 version; /* version of this structure layout */ + u64 version; /* version of this structure layout, must be first */ u32 lpid; u32 vcpu_token; /* These registers are hypervisor privileged (at least for writing) */ @@ -560,6 +563,16 @@ struct hv_guest_state { /* Latest version of hv_guest_state structure */ #define HV_GUEST_STATE_VERSION 1 +static inline int hv_guest_state_size(unsigned int version) +{ + switch (version) { + case 1: + return offsetofend(struct hv_guest_state, ppr); + default: + return -1; + } +} + #endif /* __ASSEMBLY__ */ #endif /* __KERNEL__ */ #endif /* _ASM_POWERPC_HVCALL_H */ diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book3s_hv_nested.c index 33b58549a9aa..2b433c3bacea 100644 --- a/arch/powerpc/kvm/book3s_hv_nested.c +++ b/arch/powerpc/kvm/book3s_hv_nested.c @@ -215,6 +215,45 @@ static void kvmhv_nested_mmio_needed(struct kvm_vcpu *vcpu, u64 regs_ptr) } } +static int kvmhv_read_guest_state_and_regs(struct kvm_vcpu *vcpu, + struct hv_guest_state *l2_hv, + struct pt_regs *l2_regs, + u64 hv_ptr, u64 regs_ptr) +{ + int size; + + if (kvm_vcpu_read_guest(vcpu, hv_ptr, &(l2_hv->version), + sizeof(l2_hv->version))) + return -1; + + if (kvmppc_need_byteswap(vcpu)) + l2_hv->version = swab64(l2_hv->version); + + size = hv_guest_state_size(l2_hv->version); + if (size < 0) + return -1; + + return kvm_vcpu_read_guest(vcpu, hv_ptr, l2_hv, size) || + kvm_vcpu_read_guest(vcpu, regs_ptr, l2_regs, + sizeof(struct pt_regs)); +} + +static int kvmhv_write_guest_state_and_regs(struct kvm_vcpu *vcpu, + struct hv_guest_state *l2_hv, + struct pt_regs *l2_regs, + u64 hv_ptr, u64 regs_ptr) +{ + int size; + + size = hv_guest_state_size(l2_hv->version); + if (size < 0) + return -1; + + return kvm_vcpu_write_guest(vcpu, hv_ptr, l2_hv, size) || + kvm_vcpu_write_guest(vcpu, regs_ptr, l2_regs, + sizeof(struct pt_regs)); +} + long kvmhv_enter_nested_guest(struct kvm_vcpu *vcpu) { long int err, r; @@ -235,17 +274,15 @@ long kvmhv_enter_nested_guest(struct kvm_vcpu *vcpu) hv_ptr = kvmppc_get_gpr(vcpu, 4); regs_ptr = kvmppc_get_gpr(vcpu, 5); vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu); - err = kvm_vcpu_read_guest(vcpu, hv_ptr, &l2_hv, - sizeof(struct hv_guest_state)) || - kvm_vcpu_read_guest(vcpu, regs_ptr, &l2_regs, - sizeof(struct pt_regs)); + err = kvmhv_read_guest_state_and_regs(vcpu, &l2_hv, &l2_regs, + hv_ptr, regs_ptr); srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx); if (err) return H_PARAMETER; if (kvmppc_need_byteswap(vcpu)) byteswap_hv_regs(&l2_hv); - if (l2_hv.version != HV_GUEST_STATE_VERSION) + if (l2_hv.version > HV_GUEST_STATE_VERSION) return H_P2; if (kvmppc_need_byteswap(vcpu)) @@ -325,10 +362,8 @@ long kvmhv_enter_nested_guest(struct kvm_vcpu *vcpu) byteswap_pt_regs(&l2_regs); } vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu); - err = kvm_vcpu_write_guest(vcpu, hv_ptr, &l2_hv, - sizeof(struct hv_guest_state)) || - kvm_vcpu_write_guest(vcpu, regs_ptr, &l2_regs, - sizeof(struct pt_regs)); + err = kvmhv_write_guest_state_and_regs(vcpu, &l2_hv, &l2_regs, + hv_ptr, regs_ptr); srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx); if (err) return H_AUTHORITY;
On powerpc, L1 hypervisor takes help of L0 using H_ENTER_NESTED hcall to load L2 guest state in cpu. L1 hypervisor prepares the L2 state in struct hv_guest_state and passes a pointer to it via hcall. Using that pointer, L0 reads/writes that state directly from/to L1 memory. Thus L0 must be aware of hv_guest_state layout of L1. Currently it uses version field to achieve this. i.e. If L0 hv_guest_state.version != L1 hv_guest_state.version, L0 won't allow nested kvm guest. This restriction can be loosen up a bit. L0 can be taught to understand older layout of hv_guest_state, if we restrict the new member to be added only at the end. i.e. we can allow nested guest even when L0 hv_guest_state.version > L1 hv_guest_state.version. Though, the other way around is not possible. Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com> --- arch/powerpc/include/asm/hvcall.h | 17 +++++++-- arch/powerpc/kvm/book3s_hv_nested.c | 53 ++++++++++++++++++++++++----- 2 files changed, 59 insertions(+), 11 deletions(-)