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[Xen-devel] [PATCH v5] x86/hvm: Allow guest_request vm_events coming from userspace

From: Alexandru Isaila <aisaila@xxxxxxxxxxxxxxx>

Date: Tue, 8 Aug 2017 11:27:35 +0300

Cc: sstabellini@xxxxxxxxxx, wei.liu2@xxxxxxxxxx, rcojocaru@xxxxxxxxxxxxxxx, George.Dunlap@xxxxxxxxxxxxx, ian.jackson@xxxxxxxxxxxxx, tim@xxxxxxx, tamas@xxxxxxxxxxxxx, jbeulich@xxxxxxxx, andrew.cooper3@xxxxxxxxxx, Alexandru Isaila <aisaila@xxxxxxxxxxxxxxx>

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List-id: Xen developer discussion <xen-devel.lists.xen.org>

In some introspection usecases, an in-guest agent needs to communicate with the external introspection agent. An existing mechanism is HVMOP_guest_request_vm_event, but this is restricted to kernel usecases like all other hypercalls. Introduce a mechanism whereby the introspection agent can whitelist the use of HVMOP_guest_request_vm_event directly from userspace. Signed-off-by: Alexandru Isaila <aisaila@xxxxxxxxxxxxxxx> --- Changes since V4: - Changed function mane from xc_allow_guest_userspace_event to xc_monitor_guest_userspace_event - Fixed guest_request_enabled check - Delete the guest_request_sync - Changed guest_request_userspace_event to guest_request_userspace_enabled - Moved guest_request_userspace_enabled flag from sched.h to domain.h --- tools/libxc/include/xenctrl.h | 1 + tools/libxc/xc_monitor.c | 14 ++++++++++++++ xen/arch/x86/hvm/hypercall.c | 5 +++++ xen/common/monitor.c | 13 +++++++++++++ xen/include/asm-x86/domain.h | 19 ++++++++++--------- xen/include/public/domctl.h | 21 +++++++++++---------- 6 files changed, 54 insertions(+), 19 deletions(-) diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h index bde8313..c72e12d 100644 --- a/tools/libxc/include/xenctrl.h +++ b/tools/libxc/include/xenctrl.h @@ -2022,6 +2022,7 @@ int xc_monitor_descriptor_access(xc_interface *xch, domid_t domain_id, bool enable); int xc_monitor_guest_request(xc_interface *xch, domid_t domain_id, bool enable, bool sync); +int xc_monitor_guest_userspace_event(xc_interface *xch, domid_t domain_id, bool enable); int xc_monitor_debug_exceptions(xc_interface *xch, domid_t domain_id, bool enable, bool sync); int xc_monitor_cpuid(xc_interface *xch, domid_t domain_id, bool enable); diff --git a/tools/libxc/xc_monitor.c b/tools/libxc/xc_monitor.c index b44ce93..bd8cbcf 100644 --- a/tools/libxc/xc_monitor.c +++ b/tools/libxc/xc_monitor.c @@ -161,6 +161,20 @@ int xc_monitor_guest_request(xc_interface *xch, domid_t domain_id, bool enable, return do_domctl(xch, &domctl); } +int xc_monitor_guest_userspace_event(xc_interface *xch, domid_t domain_id, bool enable) +{ + DECLARE_DOMCTL; + + domctl.cmd = XEN_DOMCTL_monitor_op; + domctl.domain = domain_id; + domctl.u.monitor_op.op = enable ? XEN_DOMCTL_MONITOR_OP_ENABLE + : XEN_DOMCTL_MONITOR_OP_DISABLE; + domctl.u.monitor_op.event = XEN_DOMCTL_MONITOR_EVENT_GUEST_USERSPACE_EVENT; + + return do_domctl(xch, &domctl); +} + + int xc_monitor_emulate_each_rep(xc_interface *xch, domid_t domain_id, bool enable) { diff --git a/xen/arch/x86/hvm/hypercall.c b/xen/arch/x86/hvm/hypercall.c index e7238ce..5742dd1 100644 --- a/xen/arch/x86/hvm/hypercall.c +++ b/xen/arch/x86/hvm/hypercall.c @@ -155,6 +155,11 @@ int hvm_hypercall(struct cpu_user_regs *regs) /* Fallthrough to permission check. */ case 4: case 2: + if ( currd->arch.monitor.guest_request_userspace_enabled && + eax == __HYPERVISOR_hvm_op && + (mode == 8 ? regs->rdi : regs->ebx) == HVMOP_guest_request_vm_event ) + break; + if ( unlikely(hvm_get_cpl(curr)) ) { default: diff --git a/xen/common/monitor.c b/xen/common/monitor.c index 451f42f..080a405 100644 --- a/xen/common/monitor.c +++ b/xen/common/monitor.c @@ -79,6 +79,19 @@ int monitor_domctl(struct domain *d, struct xen_domctl_monitor_op *mop) break; } + case XEN_DOMCTL_MONITOR_EVENT_GUEST_USERSPACE_EVENT: + { + bool old_status = d->arch.monitor.guest_request_userspace_enabled; + + if ( unlikely(old_status == requested_status) ) + return -EEXIST; + + domain_pause(d); + d->arch.monitor.guest_request_userspace_enabled = requested_status; + domain_unpause(d); + break; + } + default: /* Give arch-side the chance to handle this event */ return arch_monitor_domctl_event(d, mop); diff --git a/xen/include/asm-x86/domain.h b/xen/include/asm-x86/domain.h index c10522b..de02507 100644 --- a/xen/include/asm-x86/domain.h +++ b/xen/include/asm-x86/domain.h @@ -396,15 +396,16 @@ struct arch_domain /* Arch-specific monitor options */ struct { - unsigned int write_ctrlreg_enabled : 4; - unsigned int write_ctrlreg_sync : 4; - unsigned int write_ctrlreg_onchangeonly : 4; - unsigned int singlestep_enabled : 1; - unsigned int software_breakpoint_enabled : 1; - unsigned int debug_exception_enabled : 1; - unsigned int debug_exception_sync : 1; - unsigned int cpuid_enabled : 1; - unsigned int descriptor_access_enabled : 1; + unsigned int write_ctrlreg_enabled : 4; + unsigned int write_ctrlreg_sync : 4; + unsigned int write_ctrlreg_onchangeonly : 4; + unsigned int singlestep_enabled : 1; + unsigned int software_breakpoint_enabled : 1; + unsigned int debug_exception_enabled : 1; + unsigned int debug_exception_sync : 1; + unsigned int cpuid_enabled : 1; + unsigned int descriptor_access_enabled : 1; + unsigned int guest_request_userspace_enabled : 1; struct monitor_msr_bitmap *msr_bitmap; uint64_t write_ctrlreg_mask[4]; } monitor; diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h index ff39762..870495c 100644 --- a/xen/include/public/domctl.h +++ b/xen/include/public/domctl.h @@ -1073,16 +1073,17 @@ DEFINE_XEN_GUEST_HANDLE(xen_domctl_psr_cmt_op_t); #define XEN_DOMCTL_MONITOR_OP_GET_CAPABILITIES 2 #define XEN_DOMCTL_MONITOR_OP_EMULATE_EACH_REP 3 -#define XEN_DOMCTL_MONITOR_EVENT_WRITE_CTRLREG 0 -#define XEN_DOMCTL_MONITOR_EVENT_MOV_TO_MSR 1 -#define XEN_DOMCTL_MONITOR_EVENT_SINGLESTEP 2 -#define XEN_DOMCTL_MONITOR_EVENT_SOFTWARE_BREAKPOINT 3 -#define XEN_DOMCTL_MONITOR_EVENT_GUEST_REQUEST 4 -#define XEN_DOMCTL_MONITOR_EVENT_DEBUG_EXCEPTION 5 -#define XEN_DOMCTL_MONITOR_EVENT_CPUID 6 -#define XEN_DOMCTL_MONITOR_EVENT_PRIVILEGED_CALL 7 -#define XEN_DOMCTL_MONITOR_EVENT_INTERRUPT 8 -#define XEN_DOMCTL_MONITOR_EVENT_DESC_ACCESS 9 +#define XEN_DOMCTL_MONITOR_EVENT_WRITE_CTRLREG 0 +#define XEN_DOMCTL_MONITOR_EVENT_MOV_TO_MSR 1 +#define XEN_DOMCTL_MONITOR_EVENT_SINGLESTEP 2 +#define XEN_DOMCTL_MONITOR_EVENT_SOFTWARE_BREAKPOINT 3 +#define XEN_DOMCTL_MONITOR_EVENT_GUEST_REQUEST 4 +#define XEN_DOMCTL_MONITOR_EVENT_DEBUG_EXCEPTION 5 +#define XEN_DOMCTL_MONITOR_EVENT_CPUID 6 +#define XEN_DOMCTL_MONITOR_EVENT_PRIVILEGED_CALL 7 +#define XEN_DOMCTL_MONITOR_EVENT_INTERRUPT 8 +#define XEN_DOMCTL_MONITOR_EVENT_DESC_ACCESS 9 +#define XEN_DOMCTL_MONITOR_EVENT_GUEST_USERSPACE_EVENT 10 struct xen_domctl_monitor_op { uint32_t op; /* XEN_DOMCTL_MONITOR_OP_* */ -- 2.7.4 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel

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