On Tue, 12 Jan 2021 15:45:00 +1100 David Gibson <da...@gibson.dropbear.id.au> wrote:
> Currently the "memory-encryption" property is only looked at once we > get to kvm_init(). Although protection of guest memory from the > hypervisor isn't something that could really ever work with TCG, it's > not conceptually tied to the KVM accelerator. > > In addition, the way the string property is resolved to an object is > almost identical to how a QOM link property is handled. > > So, create a new "confidential-guest-support" link property which sets > this QOM interface link directly in the machine. For compatibility we > keep the "memory-encryption" property, but now implemented in terms of > the new property. > Do we really want to keep "memory-encryption" in the long term ? If not, then maybe engage the deprecation process and add a warning in machine_set_memory_encryption() ? Apart from that, LGTM: Reviewed-by: Greg Kurz <gr...@kaod.org> > Signed-off-by: David Gibson <da...@gibson.dropbear.id.au> > --- > accel/kvm/kvm-all.c | 5 +++-- > accel/kvm/sev-stub.c | 5 +++-- > hw/core/machine.c | 43 +++++++++++++++++++++++++++++++++++++------ > include/hw/boards.h | 2 +- > include/sysemu/sev.h | 2 +- > target/i386/sev.c | 32 ++------------------------------ > 6 files changed, 47 insertions(+), 42 deletions(-) > > diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c > index 260ed73ffe..28ab126f70 100644 > --- a/accel/kvm/kvm-all.c > +++ b/accel/kvm/kvm-all.c > @@ -2181,8 +2181,9 @@ static int kvm_init(MachineState *ms) > * if memory encryption object is specified then initialize the memory > * encryption context. > */ > - if (ms->memory_encryption) { > - ret = sev_guest_init(ms->memory_encryption); > + if (ms->cgs) { > + /* FIXME handle mechanisms other than SEV */ > + ret = sev_kvm_init(ms->cgs); > if (ret < 0) { > goto err; > } > diff --git a/accel/kvm/sev-stub.c b/accel/kvm/sev-stub.c > index 5db9ab8f00..3d4787ae4a 100644 > --- a/accel/kvm/sev-stub.c > +++ b/accel/kvm/sev-stub.c > @@ -15,7 +15,8 @@ > #include "qemu-common.h" > #include "sysemu/sev.h" > > -int sev_guest_init(const char *id) > +int sev_kvm_init(ConfidentialGuestSupport *cgs) > { > - return -1; > + /* SEV can't be selected if it's not compiled */ > + g_assert_not_reached(); > } > diff --git a/hw/core/machine.c b/hw/core/machine.c > index 8909117d80..94194ab82d 100644 > --- a/hw/core/machine.c > +++ b/hw/core/machine.c > @@ -32,6 +32,7 @@ > #include "hw/mem/nvdimm.h" > #include "migration/global_state.h" > #include "migration/vmstate.h" > +#include "exec/confidential-guest-support.h" > > GlobalProperty hw_compat_5_2[] = {}; > const size_t hw_compat_5_2_len = G_N_ELEMENTS(hw_compat_5_2); > @@ -427,16 +428,37 @@ static char *machine_get_memory_encryption(Object *obj, > Error **errp) > { > MachineState *ms = MACHINE(obj); > > - return g_strdup(ms->memory_encryption); > + if (ms->cgs) { > + return > g_strdup(object_get_canonical_path_component(OBJECT(ms->cgs))); > + } > + > + return NULL; > } > > static void machine_set_memory_encryption(Object *obj, const char *value, > Error **errp) > { > - MachineState *ms = MACHINE(obj); > + Object *cgs = > + object_resolve_path_component(object_get_objects_root(), value); > + > + if (!cgs) { > + error_setg(errp, "No such memory encryption object '%s'", value); > + return; > + } > > - g_free(ms->memory_encryption); > - ms->memory_encryption = g_strdup(value); > + object_property_set_link(obj, "confidential-guest-support", cgs, errp); > +} > + > +static void machine_check_confidential_guest_support(const Object *obj, > + const char *name, > + Object *new_target, > + Error **errp) > +{ > + /* > + * So far the only constraint is that the target has the > + * TYPE_CONFIDENTIAL_GUEST_SUPPORT interface, and that's checked > + * by the QOM core > + */ > } > > static bool machine_get_nvdimm(Object *obj, Error **errp) > @@ -836,6 +858,15 @@ static void machine_class_init(ObjectClass *oc, void > *data) > object_class_property_set_description(oc, "suppress-vmdesc", > "Set on to disable self-describing migration"); > > + object_class_property_add_link(oc, "confidential-guest-support", > + TYPE_CONFIDENTIAL_GUEST_SUPPORT, > + offsetof(MachineState, cgs), > + machine_check_confidential_guest_support, > + OBJ_PROP_LINK_STRONG); > + object_class_property_set_description(oc, "confidential-guest-support", > + "Set confidential guest scheme to > support"); > + > + /* For compatibility */ > object_class_property_add_str(oc, "memory-encryption", > machine_get_memory_encryption, machine_set_memory_encryption); > object_class_property_set_description(oc, "memory-encryption", > @@ -1158,9 +1189,9 @@ void machine_run_board_init(MachineState *machine) > cc->deprecation_note); > } > > - if (machine->memory_encryption) { > + if (machine->cgs) { > /* > - * With memory encryption, the host can't see the real > + * With confidential guests, the host can't see the real > * contents of RAM, so there's no point in it trying to merge > * areas. > */ > diff --git a/include/hw/boards.h b/include/hw/boards.h > index 17b1f3f0b9..1acd662fa5 100644 > --- a/include/hw/boards.h > +++ b/include/hw/boards.h > @@ -270,7 +270,7 @@ struct MachineState { > bool iommu; > bool suppress_vmdesc; > bool enable_graphics; > - char *memory_encryption; > + ConfidentialGuestSupport *cgs; > char *ram_memdev_id; > /* > * convenience alias to ram_memdev_id backend memory region > diff --git a/include/sysemu/sev.h b/include/sysemu/sev.h > index 7335e59867..3b5b1aacf1 100644 > --- a/include/sysemu/sev.h > +++ b/include/sysemu/sev.h > @@ -16,7 +16,7 @@ > > #include "sysemu/kvm.h" > > -int sev_guest_init(const char *id); > +int sev_kvm_init(ConfidentialGuestSupport *cgs); > int sev_encrypt_flash(uint8_t *ptr, uint64_t len, Error **errp); > int sev_inject_launch_secret(const char *hdr, const char *secret, > uint64_t gpa, Error **errp); > diff --git a/target/i386/sev.c b/target/i386/sev.c > index 2a4b2187d6..5399a136ad 100644 > --- a/target/i386/sev.c > +++ b/target/i386/sev.c > @@ -335,26 +335,6 @@ static const TypeInfo sev_guest_info = { > } > }; > > -static SevGuestState * > -lookup_sev_guest_info(const char *id) > -{ > - Object *obj; > - SevGuestState *info; > - > - obj = object_resolve_path_component(object_get_objects_root(), id); > - if (!obj) { > - return NULL; > - } > - > - info = (SevGuestState *) > - object_dynamic_cast(obj, TYPE_SEV_GUEST); > - if (!info) { > - return NULL; > - } > - > - return info; > -} > - > bool > sev_enabled(void) > { > @@ -682,10 +662,9 @@ sev_vm_state_change(void *opaque, int running, RunState > state) > } > } > > -int > -sev_guest_init(const char *id) > +int sev_kvm_init(ConfidentialGuestSupport *cgs) > { > - SevGuestState *sev; > + SevGuestState *sev = SEV_GUEST(cgs); > char *devname; > int ret, fw_error; > uint32_t ebx; > @@ -698,13 +677,6 @@ sev_guest_init(const char *id) > return -1; > } > > - sev = lookup_sev_guest_info(id); > - if (!sev) { > - error_report("%s: '%s' is not a valid '%s' object", > - __func__, id, TYPE_SEV_GUEST); > - goto err; > - } > - > sev_guest = sev; > sev->state = SEV_STATE_UNINIT; >