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Re: [Qemu-devel] [PATCH v4 1/1] xen-hvm.c: Add support for Xen access to
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From: |
Paul Durrant |
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Subject: |
Re: [Qemu-devel] [PATCH v4 1/1] xen-hvm.c: Add support for Xen access to vmport |
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Date: |
Fri, 17 Oct 2014 13:35:55 +0000 |
> -----Original Message-----
> From: Don Slutz [mailto:address@hidden
> Sent: 17 October 2014 14:31
> To: Paul Durrant; Don Slutz; address@hidden
> Cc: address@hidden; Alexander Graf; Andreas Färber;
> Anthony Liguori; Marcel Apfelbaum; Markus Armbruster; Michael S. Tsirkin;
> Stefano Stabellini
> Subject: Re: [PATCH v4 1/1] xen-hvm.c: Add support for Xen access to
> vmport
>
> On 10/17/14 08:34, Paul Durrant wrote:
> >> -----Original Message-----
> >> From: Don Slutz [mailto:address@hidden
> >> Sent: 17 October 2014 13:14
> >> To: address@hidden; Paul Durrant
> >> Cc: address@hidden; Alexander Graf; Andreas Färber;
> >> Anthony Liguori; Don Slutz; Marcel Apfelbaum; Markus Armbruster;
> Michael
> >> S. Tsirkin; Stefano Stabellini
> >> Subject: [PATCH v4 1/1] xen-hvm.c: Add support for Xen access to vmport
> >>
> >> This adds synchronisation of the 6 vcpu registers (only 32bits of
> >> them) that vmport.c needs between Xen and QEMU.
> >>
> >> This is to avoid a 2nd and 3rd exchange between QEMU and Xen to
> >> fetch and put these 6 vcpu registers used by the code in vmport.c
> >> and vmmouse.c
> >>
> >> The registers are passed in the new shared page provided by
> >> HVM_PARAM_VMPORT_IOREQ_PFN.
> >>
> >> Add new array to XenIOState that allows selection of current_cpu by
> >> ioreq_id.
> >>
> >> Now pass XenIOState to handle_ioreq().
> >>
> >> Add new routines regs_to_cpu(), regs_from_cpu(), and
> >> handle_vmport_ioreq().
> >>
> >> Signed-off-by: Don Slutz <address@hidden>
> >> ---
> >> include/hw/xen/xen_common.h | 15 ++++++
> >> xen-hvm.c | 121
> >> ++++++++++++++++++++++++++++++++++++++++++--
> >> 2 files changed, 131 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/include/hw/xen/xen_common.h
> >> b/include/hw/xen/xen_common.h
> >> index 07731b9..9542756 100644
> >> --- a/include/hw/xen/xen_common.h
> >> +++ b/include/hw/xen/xen_common.h
> >> @@ -164,4 +164,19 @@ void destroy_hvm_domain(bool reboot);
> >> /* shutdown/destroy current domain because of an error */
> >> void xen_shutdown_fatal_error(const char *fmt, ...) GCC_FMT_ATTR(1,
> 2);
> >>
> >> +#ifdef HVM_PARAM_VMPORT_IOREQ_PFN
> >> +static inline int xen_get_vmport_ioreq_pfn(XenXC xc, domid_t dom,
> >> + unsigned long
> >> *vmport_ioreq_pfn)
> >> +{
> >> + return xc_get_hvm_param(xc, dom,
> >> HVM_PARAM_VMPORT_IOREQ_PFN,
> >> + vmport_ioreq_pfn);
> >> +}
> >> +#else
> >> +static inline int xen_get_vmport_ioreq_pfn(XenXC xc, domid_t dom,
> >> + unsigned long
> >> *vmport_ioreq_pfn)
> >> +{
> >> + return -ENOSYS;
> >> +}
> >> +#endif
> >> +
> >> #endif /* QEMU_HW_XEN_COMMON_H */
> >> diff --git a/xen-hvm.c b/xen-hvm.c
> >> index 05e522c..17b3cbd 100644
> >> --- a/xen-hvm.c
> >> +++ b/xen-hvm.c
> >> @@ -41,6 +41,29 @@ static MemoryRegion *framebuffer;
> >> static bool xen_in_migration;
> >>
> >> /* Compatibility with older version */
> >> +
> >> +/* This allows QEMU to build on a system that has Xen 4.5 or earlier
> >> + * installed. This here (not in hw/xen/xen_common.h) because
> >> xen/hvm/ioreq.h
> >> + * needs to be included before this block and hw/xen/xen_common.h
> >> needs to
> >> + * be included before xen/hvm/ioreq.h
> >> + */
> >> +#ifndef IOREQ_TYPE_VMWARE_PORT
> >> +#define IOREQ_TYPE_VMWARE_PORT 3
> >> +struct vmware_ioreq {
> >> + uint32_t esi;
> >> + uint32_t edi;
> >> + uint32_t ebx;
> >> + uint32_t ecx;
> >> + uint32_t edx;
> >> +};
> >> +typedef struct vmware_ioreq vmware_ioreq_t;
> > This struct is not really a request any more. Maybe vmware_regs_t?
>
> Sure.
>
> >> +
> >> +struct shared_vmport_iopage {
> >> + struct vmware_ioreq vcpu_vmport_ioreq[1];
> >> +};
> >> +typedef struct shared_vmport_iopage shared_vmport_iopage_t;
> >> +#endif
> >> +
> >> #if __XEN_LATEST_INTERFACE_VERSION__ < 0x0003020a
> >> static inline uint32_t xen_vcpu_eport(shared_iopage_t *shared_page,
> int i)
> >> {
> >> @@ -79,8 +102,10 @@ typedef struct XenPhysmap {
> >>
> >> typedef struct XenIOState {
> >> shared_iopage_t *shared_page;
> >> + shared_vmport_iopage_t *shared_vmport_page;
> >> buffered_iopage_t *buffered_io_page;
> >> QEMUTimer *buffered_io_timer;
> >> + CPUState **cpu_by_ioreq_id;
> > This name implies the array is indexed by an id carries in the ioreq. That
> doesn't seem to be the case; it's just indexed by guest vcpu id isn't it?
>
> Yes. How about cpu_by_vcpu_id ?
Ok.
>
> >> /* the evtchn port for polling the notification, */
> >> evtchn_port_t *ioreq_local_port;
> >> /* evtchn local port for buffered io */
> >> @@ -101,6 +126,8 @@ typedef struct XenIOState {
> >> Notifier wakeup;
> >> } XenIOState;
> >>
> >> +static void handle_ioreq(XenIOState *state, ioreq_t *req);
> >> +
> >> /* Xen specific function for piix pci */
> >>
> >> int xen_pci_slot_get_pirq(PCIDevice *pci_dev, int irq_num)
> >> @@ -610,6 +637,20 @@ static ioreq_t
> >> *cpu_get_ioreq_from_shared_memory(XenIOState *state, int vcpu)
> >> return req;
> >> }
> >>
> >> +/* get the vmport ioreq packets from share mem */
> >> +static vmware_ioreq_t
> *cpu_get_vmport_ioreq_from_shared_memory(
> > Is this worth its own function? I can only see one use of it in
> handle_vmport_ioreq below...
>
> Will move it in-line. I was just following
> cpu_get_ioreq_from_shared_memory which also has 1 use.
>
> >> + XenIOState *state, int vcpu)
> >> +{
> >> + vmware_ioreq_t *vmport_req;
> >> +
> >> + assert(state->shared_vmport_page);
> >> + vmport_req = &state->shared_vmport_page-
> >>> vcpu_vmport_ioreq[vcpu];
> >> +
> >> + xen_rmb(); /* see IOREQ_READY /then/ read contents of ioreq */
> > I don't think that comment is applicable here, and I don't think you need
> the barrier anyway.
>
> I was not sure either way, so went with the safe way. Will drop.
>
> >> +
> >> + return vmport_req;
> >> +}
> >> +
> >> /* use poll to get the port notification */
> >> /* ioreq_vec--out,the */
> >> /* retval--the number of ioreq packet */
> >> @@ -773,7 +814,50 @@ static void cpu_ioreq_move(ioreq_t *req)
> >> }
> >> }
> >>
> >> -static void handle_ioreq(ioreq_t *req)
> >> +static void regs_to_cpu(XenIOState *state, vmware_ioreq_t
> *vmport_req,
> >> + ioreq_t *req)
> >> +{
> >> + X86CPU *cpu;
> >> + CPUX86State *env;
> >> +
> >> + current_cpu = state->cpu_by_ioreq_id[state->send_vcpu];
> >> + cpu = X86_CPU(current_cpu);
> >> + env = &cpu->env;
> >> + env->regs[R_EAX] = req->data;
> >> + env->regs[R_EBX] = vmport_req->ebx;
> >> + env->regs[R_ECX] = vmport_req->ecx;
> >> + env->regs[R_EDX] = vmport_req->edx;
> >> + env->regs[R_ESI] = vmport_req->esi;
> >> + env->regs[R_EDI] = vmport_req->edi;
> >> +}
> >> +
> >> +static void regs_from_cpu(XenIOState *state, vmware_ioreq_t
> >> *vmport_req,
> >> + ioreq_t *req)
> >> +{
> >> + X86CPU *cpu = X86_CPU(current_cpu);
> >> + CPUX86State *env = &cpu->env;
> >> +
> >> + assert(sizeof(*vmport_req) <= sizeof(*req));
> > Why?
>
> Since there is 1 page of ioreq_t indexed by vcpu id this checks that
> the 1 page of vmport data has at least the same number of vcpu
> slots.
Does it? It looks like it checks that the size of the vmware_ioreq_t structure
is less than or equal to the size of the ioreq_t structure to me. I see nothing
checking number of array elements.
Paul
> This prevents a bad memory read. Looks to not be the right place
> for this, will move.
>
> >> +
> >> + vmport_req->ebx = env->regs[R_EBX];
> >> + vmport_req->ecx = env->regs[R_ECX];
> >> + vmport_req->edx = env->regs[R_EDX];
> >> + vmport_req->esi = env->regs[R_ESI];
> >> + vmport_req->edi = env->regs[R_EDI];
> >> + current_cpu = NULL;
> >> +}
> >> +
> >> +static void handle_vmport_ioreq(XenIOState *state, ioreq_t *req)
> >> +{
> >> + vmware_ioreq_t *vmport_req =
> >> + cpu_get_vmport_ioreq_from_shared_memory(state, state-
> >>> send_vcpu);
> >> +
> >> + regs_to_cpu(state, vmport_req, req);
> >> + cpu_ioreq_pio(req);
> >> + regs_from_cpu(state, vmport_req, req);
> > state appears to be unused in this function, and you could avoid passing it
> to both of them by setting current_cpu here couldn't you?
>
> Yes, will move state code here.
>
> -Don Slutz
>
> > Paul
> >
> >> +}
> >> +
> >> +static void handle_ioreq(XenIOState *state, ioreq_t *req)
> >> {
> >> if (!req->data_is_ptr && (req->dir == IOREQ_WRITE) &&
> >> (req->size < sizeof (target_ulong))) {
> >> @@ -787,6 +871,9 @@ static void handle_ioreq(ioreq_t *req)
> >> case IOREQ_TYPE_COPY:
> >> cpu_ioreq_move(req);
> >> break;
> >> + case IOREQ_TYPE_VMWARE_PORT:
> >> + handle_vmport_ioreq(state, req);
> >> + break;
> >> case IOREQ_TYPE_TIMEOFFSET:
> >> break;
> >> case IOREQ_TYPE_INVALIDATE:
> >> @@ -828,7 +915,7 @@ static int handle_buffered_iopage(XenIOState
> >> *state)
> >> req.data |= ((uint64_t)buf_req->data) << 32;
> >> }
> >>
> >> - handle_ioreq(&req);
> >> + handle_ioreq(state, &req);
> >>
> >> xen_mb();
> >> state->buffered_io_page->read_pointer += qw ? 2 : 1;
> >> @@ -857,14 +944,16 @@ static void cpu_handle_ioreq(void *opaque)
> >>
> >> handle_buffered_iopage(state);
> >> if (req) {
> >> - handle_ioreq(req);
> >> + handle_ioreq(state, req);
> >>
> >> if (req->state != STATE_IOREQ_INPROCESS) {
> >> fprintf(stderr, "Badness in I/O request ... not in
> >> service?!: "
> >> "%x, ptr: %x, port: %"PRIx64", "
> >> - "data: %"PRIx64", count: %" FMT_ioreq_size ", size: %"
> >> FMT_ioreq_size "\n",
> >> + "data: %"PRIx64", count: %" FMT_ioreq_size
> >> + ", size: %" FMT_ioreq_size
> >> + ", type: %"FMT_ioreq_size"\n",
> >> req->state, req->data_is_ptr, req->addr,
> >> - req->data, req->count, req->size);
> >> + req->data, req->count, req->size, req->type);
> >> destroy_hvm_domain(false);
> >> return;
> >> }
> >> @@ -904,6 +993,14 @@ static void xen_main_loop_prepare(XenIOState
> >> *state)
> >> state);
> >>
> >> if (evtchn_fd != -1) {
> >> + CPUState *cpu_state;
> >> +
> >> + DPRINTF("%s: Init cpu_by_ioreq_id\n", __func__);
> >> + CPU_FOREACH(cpu_state) {
> >> + DPRINTF("%s: cpu_by_ioreq_id[%d]=%p\n",
> >> + __func__, cpu_state->cpu_index, cpu_state);
> >> + state->cpu_by_ioreq_id[cpu_state->cpu_index] = cpu_state;
> >> + }
> >> qemu_set_fd_handler(evtchn_fd, cpu_handle_ioreq, NULL, state);
> >> }
> >> }
> >> @@ -1020,6 +1117,17 @@ int xen_hvm_init(ram_addr_t
> >> *below_4g_mem_size, ram_addr_t *above_4g_mem_size,
> >> errno, xen_xc);
> >> }
> >>
> >> + if (!xen_get_vmport_ioreq_pfn(xen_xc, xen_domid, &ioreq_pfn)) {
> >> + DPRINTF("shared vmport page at pfn %lx\n", ioreq_pfn);
> >> + state->shared_vmport_page =
> >> + xc_map_foreign_range(xen_xc, xen_domid, XC_PAGE_SIZE,
> >> + PROT_READ|PROT_WRITE, ioreq_pfn);
> >> + if (state->shared_vmport_page == NULL) {
> >> + hw_error("map shared vmport IO page returned error %d
> handle="
> >> + XC_INTERFACE_FMT, errno, xen_xc);
> >> + }
> >> + }
> >> +
> >> xc_get_hvm_param(xen_xc, xen_domid,
> HVM_PARAM_BUFIOREQ_PFN,
> >> &ioreq_pfn);
> >> DPRINTF("buffered io page at pfn %lx\n", ioreq_pfn);
> >> state->buffered_io_page = xc_map_foreign_range(xen_xc,
> xen_domid,
> >> XC_PAGE_SIZE,
> >> @@ -1028,6 +1136,9 @@ int xen_hvm_init(ram_addr_t
> >> *below_4g_mem_size, ram_addr_t *above_4g_mem_size,
> >> hw_error("map buffered IO page returned error %d", errno);
> >> }
> >>
> >> + /* Note: cpus is empty at this point in init */
> >> + state->cpu_by_ioreq_id = g_malloc0(max_cpus * sizeof(CPUState *));
> >> +
> >> state->ioreq_local_port = g_malloc0(max_cpus * sizeof
> (evtchn_port_t));
> >>
> >> /* FIXME: how about if we overflow the page here? */
> >> --
> >> 1.8.4