| Message ID | 20200221083014.29274-1-aisaila@bitdefender.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [V4] x86/altp2m: Hypercall to set altp2m view visibility | expand |
On 21.02.2020 09:30, Alexandru Stefan ISAILA wrote: > @@ -4835,6 +4836,26 @@ static int do_altp2m_op( > break; > } > > + case HVMOP_altp2m_set_visibility: > + { > + uint16_t idx = a.u.set_visibility.altp2m_idx; > + > + if ( a.u.set_visibility.pad || > + idx >= min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) || Why min() here? You only access MAX_EPTP-dimensioned arrays afaics. If this is intentional, I think it deserves a comment. > + d->arch.altp2m_eptp[array_index_nospec(idx, MAX_EPTP)] == > + mfn_x(INVALID_MFN) ) > + rc = -EINVAL; > + else if ( !altp2m_active(d) ) > + rc = -EOPNOTSUPP; > + else if ( a.u.set_visibility.visible ) > + d->arch.altp2m_working_eptp[array_index_nospec(idx, MAX_EPTP)] = > + d->arch.altp2m_eptp[array_index_nospec(idx, MAX_EPTP)]; > + else > + d->arch.altp2m_working_eptp[array_index_nospec(idx, MAX_EPTP)] = > + mfn_x(INVALID_MFN); > + break; You don't seem to be holding any locks. At the very least this means the in-range-index-is-valid check further up will have become stale by the time you actually consume the slot. > @@ -2638,7 +2639,9 @@ int p2m_destroy_altp2m_by_id(struct domain *d, unsigned int idx) > { > p2m_reset_altp2m(d, idx, ALTP2M_DEACTIVATE); > d->arch.altp2m_eptp[array_index_nospec(idx, MAX_EPTP)] = > - mfn_x(INVALID_MFN); > + mfn_x(INVALID_MFN); > + d->arch.altp2m_working_eptp[array_index_nospec(idx, MAX_EPTP)] = > + mfn_x(INVALID_MFN); I appreciate you also adjusting the bogus indentation of the pre- existing line. Jan
On 21.02.2020 18:39, Jan Beulich wrote: > On 21.02.2020 09:30, Alexandru Stefan ISAILA wrote: >> @@ -4835,6 +4836,26 @@ static int do_altp2m_op( >> break; >> } >> >> + case HVMOP_altp2m_set_visibility: >> + { >> + uint16_t idx = a.u.set_visibility.altp2m_idx; >> + >> + if ( a.u.set_visibility.pad || >> + idx >= min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) || > > Why min() here? You only access MAX_EPTP-dimensioned arrays afaics. If > this is intentional, I think it deserves a comment. I have min() here because the altp2m index should not be grater then MAX_ALTP2M. I know this is used as altp2m_eptp() index but the two are coupled. > >> + d->arch.altp2m_eptp[array_index_nospec(idx, MAX_EPTP)] == >> + mfn_x(INVALID_MFN) ) >> + rc = -EINVAL; >> + else if ( !altp2m_active(d) ) >> + rc = -EOPNOTSUPP; >> + else if ( a.u.set_visibility.visible ) >> + d->arch.altp2m_working_eptp[array_index_nospec(idx, MAX_EPTP)] = >> + d->arch.altp2m_eptp[array_index_nospec(idx, MAX_EPTP)]; >> + else >> + d->arch.altp2m_working_eptp[array_index_nospec(idx, MAX_EPTP)] = >> + mfn_x(INVALID_MFN); >> + break; > > You don't seem to be holding any locks. At the very least this means > the in-range-index-is-valid check further up will have become stale > by the time you actually consume the slot. > Good thing to point this out here. I will add altp2m_list_lock/unlock(d) to guard this check and operation. >> @@ -2638,7 +2639,9 @@ int p2m_destroy_altp2m_by_id(struct domain *d, unsigned int idx) >> { >> p2m_reset_altp2m(d, idx, ALTP2M_DEACTIVATE); >> d->arch.altp2m_eptp[array_index_nospec(idx, MAX_EPTP)] = >> - mfn_x(INVALID_MFN); >> + mfn_x(INVALID_MFN); >> + d->arch.altp2m_working_eptp[array_index_nospec(idx, MAX_EPTP)] = >> + mfn_x(INVALID_MFN); > > I appreciate you also adjusting the bogus indentation of the pre- > existing line. > Thanks, Alex
On 24.02.2020 11:06, Alexandru Stefan ISAILA wrote: > > > On 21.02.2020 18:39, Jan Beulich wrote: >> On 21.02.2020 09:30, Alexandru Stefan ISAILA wrote: >>> @@ -4835,6 +4836,26 @@ static int do_altp2m_op( >>> break; >>> } >>> >>> + case HVMOP_altp2m_set_visibility: >>> + { >>> + uint16_t idx = a.u.set_visibility.altp2m_idx; >>> + >>> + if ( a.u.set_visibility.pad || >>> + idx >= min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) || >> >> Why min() here? You only access MAX_EPTP-dimensioned arrays afaics. If >> this is intentional, I think it deserves a comment. > > I have min() here because the altp2m index should not be grater then > MAX_ALTP2M. I know this is used as altp2m_eptp() index but the two are > coupled. > >> >>> + d->arch.altp2m_eptp[array_index_nospec(idx, MAX_EPTP)] == >>> + mfn_x(INVALID_MFN) ) >>> + rc = -EINVAL; >>> + else if ( !altp2m_active(d) ) >>> + rc = -EOPNOTSUPP; >>> + else if ( a.u.set_visibility.visible ) >>> + d->arch.altp2m_working_eptp[array_index_nospec(idx, MAX_EPTP)] = >>> + d->arch.altp2m_eptp[array_index_nospec(idx, MAX_EPTP)]; >>> + else >>> + d->arch.altp2m_working_eptp[array_index_nospec(idx, MAX_EPTP)] = >>> + mfn_x(INVALID_MFN); >>> + break; >> >> You don't seem to be holding any locks. At the very least this means >> the in-range-index-is-valid check further up will have become stale >> by the time you actually consume the slot. >> > > Good thing to point this out here. I will add altp2m_list_lock/unlock(d) > to guard this check and operation. I think it's better to move all the altp2m things in a new function, something like p2m_set_altp2m_view_visibility(), in p2m.c. This way there will be no additional include needed. Alex
diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h index 99552a5f73..b26fccc989 100644 --- a/tools/libxc/include/xenctrl.h +++ b/tools/libxc/include/xenctrl.h @@ -1943,6 +1943,13 @@ int xc_altp2m_change_gfn(xc_interface *handle, uint32_t domid, xen_pfn_t new_gfn); int xc_altp2m_get_vcpu_p2m_idx(xc_interface *handle, uint32_t domid, uint32_t vcpuid, uint16_t *p2midx); +/* + * Set view visibility for xc_altp2m_switch_to_view and vmfunc. + * Note: If altp2m mode is set to mixed the guest is able to change the view + * visibility and then call vmfunc. + */ +int xc_altp2m_set_visibility(xc_interface *handle, uint32_t domid, + uint16_t view_id, bool visible); /** * Mem paging operations. diff --git a/tools/libxc/xc_altp2m.c b/tools/libxc/xc_altp2m.c index 46fb725806..6987c9541f 100644 --- a/tools/libxc/xc_altp2m.c +++ b/tools/libxc/xc_altp2m.c @@ -410,3 +410,27 @@ int xc_altp2m_get_vcpu_p2m_idx(xc_interface *handle, uint32_t domid, xc_hypercall_buffer_free(handle, arg); return rc; } + +int xc_altp2m_set_visibility(xc_interface *handle, uint32_t domid, + uint16_t view_id, bool visible) +{ + int rc; + + DECLARE_HYPERCALL_BUFFER(xen_hvm_altp2m_op_t, arg); + + arg = xc_hypercall_buffer_alloc(handle, arg, sizeof(*arg)); + if ( arg == NULL ) + return -1; + + arg->version = HVMOP_ALTP2M_INTERFACE_VERSION; + arg->cmd = HVMOP_altp2m_set_visibility; + arg->domain = domid; + arg->u.set_visibility.altp2m_idx = view_id; + arg->u.set_visibility.visible = visible; + + rc = xencall2(handle->xcall, __HYPERVISOR_hvm_op, HVMOP_altp2m, + HYPERCALL_BUFFER_AS_ARG(arg)); + + xc_hypercall_buffer_free(handle, arg); + return rc; +} diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c index 00a9e70b7c..d1ce0f869e 100644 --- a/xen/arch/x86/hvm/hvm.c +++ b/xen/arch/x86/hvm/hvm.c @@ -4558,6 +4558,7 @@ static int do_altp2m_op( case HVMOP_altp2m_get_mem_access: case HVMOP_altp2m_change_gfn: case HVMOP_altp2m_get_p2m_idx: + case HVMOP_altp2m_set_visibility: break; default: @@ -4835,6 +4836,26 @@ static int do_altp2m_op( break; } + case HVMOP_altp2m_set_visibility: + { + uint16_t idx = a.u.set_visibility.altp2m_idx; + + if ( a.u.set_visibility.pad || + idx >= min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) || + d->arch.altp2m_eptp[array_index_nospec(idx, MAX_EPTP)] == + mfn_x(INVALID_MFN) ) + rc = -EINVAL; + else if ( !altp2m_active(d) ) + rc = -EOPNOTSUPP; + else if ( a.u.set_visibility.visible ) + d->arch.altp2m_working_eptp[array_index_nospec(idx, MAX_EPTP)] = + d->arch.altp2m_eptp[array_index_nospec(idx, MAX_EPTP)]; + else + d->arch.altp2m_working_eptp[array_index_nospec(idx, MAX_EPTP)] = + mfn_x(INVALID_MFN); + break; + } + default: ASSERT_UNREACHABLE(); } diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c index bc2f48bf2c..90de909fec 100644 --- a/xen/arch/x86/hvm/vmx/vmx.c +++ b/xen/arch/x86/hvm/vmx/vmx.c @@ -2140,7 +2140,7 @@ static void vmx_vcpu_update_vmfunc_ve(struct vcpu *v) { v->arch.hvm.vmx.secondary_exec_control |= mask; __vmwrite(VM_FUNCTION_CONTROL, VMX_VMFUNC_EPTP_SWITCHING); - __vmwrite(EPTP_LIST_ADDR, virt_to_maddr(d->arch.altp2m_eptp)); + __vmwrite(EPTP_LIST_ADDR, virt_to_maddr(d->arch.altp2m_working_eptp)); if ( cpu_has_vmx_virt_exceptions ) { diff --git a/xen/arch/x86/mm/hap/hap.c b/xen/arch/x86/mm/hap/hap.c index 3d93f3451c..5969ec8922 100644 --- a/xen/arch/x86/mm/hap/hap.c +++ b/xen/arch/x86/mm/hap/hap.c @@ -488,8 +488,17 @@ int hap_enable(struct domain *d, u32 mode) goto out; } + if ( (d->arch.altp2m_working_eptp = alloc_xenheap_page()) == NULL ) + { + rv = -ENOMEM; + goto out; + } + for ( i = 0; i < MAX_EPTP; i++ ) + { d->arch.altp2m_eptp[i] = mfn_x(INVALID_MFN); + d->arch.altp2m_working_eptp[i] = mfn_x(INVALID_MFN); + } for ( i = 0; i < MAX_ALTP2M; i++ ) { @@ -523,6 +532,12 @@ void hap_final_teardown(struct domain *d) d->arch.altp2m_eptp = NULL; } + if ( d->arch.altp2m_working_eptp ) + { + free_xenheap_page(d->arch.altp2m_working_eptp); + d->arch.altp2m_working_eptp = NULL; + } + for ( i = 0; i < MAX_ALTP2M; i++ ) p2m_teardown(d->arch.altp2m_p2m[i]); } diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c index eb0f0edfef..6539ca619b 100644 --- a/xen/arch/x86/mm/p2m-ept.c +++ b/xen/arch/x86/mm/p2m-ept.c @@ -1368,6 +1368,7 @@ void p2m_init_altp2m_ept(struct domain *d, unsigned int i) ept = &p2m->ept; ept->mfn = pagetable_get_pfn(p2m_get_pagetable(p2m)); d->arch.altp2m_eptp[array_index_nospec(i, MAX_EPTP)] = ept->eptp; + d->arch.altp2m_working_eptp[array_index_nospec(i, MAX_EPTP)] = ept->eptp; } unsigned int p2m_find_altp2m_by_eptp(struct domain *d, uint64_t eptp) diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c index 9f1c29d7ef..13b96715ba 100644 --- a/xen/arch/x86/mm/p2m.c +++ b/xen/arch/x86/mm/p2m.c @@ -2519,6 +2519,7 @@ void p2m_flush_altp2m(struct domain *d) { p2m_reset_altp2m(d, i, ALTP2M_DEACTIVATE); d->arch.altp2m_eptp[i] = mfn_x(INVALID_MFN); + d->arch.altp2m_working_eptp[i] = mfn_x(INVALID_MFN); } altp2m_list_unlock(d); @@ -2638,7 +2639,9 @@ int p2m_destroy_altp2m_by_id(struct domain *d, unsigned int idx) { p2m_reset_altp2m(d, idx, ALTP2M_DEACTIVATE); d->arch.altp2m_eptp[array_index_nospec(idx, MAX_EPTP)] = - mfn_x(INVALID_MFN); + mfn_x(INVALID_MFN); + d->arch.altp2m_working_eptp[array_index_nospec(idx, MAX_EPTP)] = + mfn_x(INVALID_MFN); rc = 0; } } @@ -2665,7 +2668,7 @@ int p2m_switch_domain_altp2m_by_id(struct domain *d, unsigned int idx) rc = -EINVAL; altp2m_list_lock(d); - if ( d->arch.altp2m_eptp[idx] != mfn_x(INVALID_MFN) ) + if ( d->arch.altp2m_working_eptp[idx] != mfn_x(INVALID_MFN) ) { for_each_vcpu( d, v ) if ( idx != vcpu_altp2m(v).p2midx ) diff --git a/xen/include/asm-x86/domain.h b/xen/include/asm-x86/domain.h index 1843c76d1a..b039717778 100644 --- a/xen/include/asm-x86/domain.h +++ b/xen/include/asm-x86/domain.h @@ -326,6 +326,7 @@ struct arch_domain struct p2m_domain *altp2m_p2m[MAX_ALTP2M]; mm_lock_t altp2m_list_lock; uint64_t *altp2m_eptp; + uint64_t *altp2m_working_eptp; #endif /* NB. protected by d->event_lock and by irq_desc[irq].lock */ diff --git a/xen/include/public/hvm/hvm_op.h b/xen/include/public/hvm/hvm_op.h index b599d3cbd0..870ec52060 100644 --- a/xen/include/public/hvm/hvm_op.h +++ b/xen/include/public/hvm/hvm_op.h @@ -318,6 +318,12 @@ struct xen_hvm_altp2m_get_vcpu_p2m_idx { uint16_t altp2m_idx; }; +struct xen_hvm_altp2m_set_visibility { + uint16_t altp2m_idx; + uint8_t visible; + uint8_t pad; +}; + struct xen_hvm_altp2m_op { uint32_t version; /* HVMOP_ALTP2M_INTERFACE_VERSION */ uint32_t cmd; @@ -350,6 +356,8 @@ struct xen_hvm_altp2m_op { #define HVMOP_altp2m_get_p2m_idx 14 /* Set the "Supress #VE" bit for a range of pages */ #define HVMOP_altp2m_set_suppress_ve_multi 15 +/* Set visibility for a given altp2m view */ +#define HVMOP_altp2m_set_visibility 16 domid_t domain; uint16_t pad1; uint32_t pad2; @@ -367,6 +375,7 @@ struct xen_hvm_altp2m_op { struct xen_hvm_altp2m_suppress_ve_multi suppress_ve_multi; struct xen_hvm_altp2m_vcpu_disable_notify disable_notify; struct xen_hvm_altp2m_get_vcpu_p2m_idx get_vcpu_p2m_idx; + struct xen_hvm_altp2m_set_visibility set_visibility; uint8_t pad[64]; } u; };
At this moment a guest can call vmfunc to change the altp2m view. This should be limited in order to avoid any unwanted view switch. The new xc_altp2m_set_visibility() solves this by making views invisible to vmfunc. This is done by having a separate arch.altp2m_working_eptp that is populated and made invalid in the same places as altp2m_eptp. This is written to EPTP_LIST_ADDR. The views are made in/visible by marking them with INVALID_MFN or copying them back from altp2m_eptp. To have consistency the visibility also applies to p2m_switch_domain_altp2m_by_id(). Note: If altp2m mode is set to mixed the guest is able to change the view visibility and then call vmfunc. Signed-off-by: Alexandru Isaila <aisaila@bitdefender.com> --- CC: Ian Jackson <ian.jackson@eu.citrix.com> CC: Wei Liu <wl@xen.org> CC: Andrew Cooper <andrew.cooper3@citrix.com> CC: George Dunlap <George.Dunlap@eu.citrix.com> CC: Jan Beulich <jbeulich@suse.com> CC: Julien Grall <julien@xen.org> CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> CC: Stefano Stabellini <sstabellini@kernel.org> CC: "Roger Pau Monné" <roger.pau@citrix.com> CC: Jun Nakajima <jun.nakajima@intel.com> CC: Kevin Tian <kevin.tian@intel.com> CC: George Dunlap <george.dunlap@eu.citrix.com> --- Changes since V3: - Change var name form altp2m_idx to idx to shorten line length - Add bounds check for idx - Update commit message - Add comment in xenctrl.h. Changes since V2: - Drop hap_enabled() check - Reduce the indentation depth in hvm.c - Fix assignment indentation - Drop pad2. Changes since V1: - Drop double view from title. --- tools/libxc/include/xenctrl.h | 7 +++++++ tools/libxc/xc_altp2m.c | 24 ++++++++++++++++++++++++ xen/arch/x86/hvm/hvm.c | 21 +++++++++++++++++++++ xen/arch/x86/hvm/vmx/vmx.c | 2 +- xen/arch/x86/mm/hap/hap.c | 15 +++++++++++++++ xen/arch/x86/mm/p2m-ept.c | 1 + xen/arch/x86/mm/p2m.c | 7 +++++-- xen/include/asm-x86/domain.h | 1 + xen/include/public/hvm/hvm_op.h | 9 +++++++++ 9 files changed, 84 insertions(+), 3 deletions(-)