Re: [Qemu-devel] [PATCH 2/2] spapr: initial implementation for H_TPM_COMM hcall

[Michael Roth]

Quoting David Gibson (2019-07-12 01:46:19)
> On Thu, Jul 11, 2019 at 08:19:34PM -0500, Michael Roth wrote:
> > This implements the H_TPM_COMM hypercall, which is used by an
> > Ultravisor to pass TPM commands directly to the host's TPM device, or
> > a TPM Resource Manager associated with the device.
> > 
> > This also introduces a new pseries machine option which is used to
> > configure what TPM device to pass commands to, for example:
> > 
> >   -machine pseries,...,tpm-device-file=/dev/tmprm0
> 
> Bolting this into yet another machine parameter seems kind of ugly.
> Wouldn't it make more sense to treat this as an virtual device (say
> "spapr-vtpm").  Adding that device would enable the hcall, and would
> have properties for the back end host device.

That does sound nicer.

Originally I had SpaprMachineClass implement the TYPE_TPM_IF interface so
we could define a TPM backend via -tpmdev passthrough,path=..., but after
some discussion with the TPM maintainer it didn't quite work for the main
use-case of passing through a TPM Resource Manager since it isn't suitable
for full vTPM front-ends (since multiple guests can interfere with each
other's operations when running the full gamut of TPM functionality).

I hadn't consider a stand-alone -device implementation though. It's not
a proper VIO or PCI device so there's no proper bus to attach it to. I
guess we would just make it a direct child of SpaprMachineState (sort
of like SpaprDrcClass), then we could define it via something like
-object spapr-tpm-proxy,path=....

I'll go ahead and give that a shot, assuming it seems reasonable to you.

> 
> > By default, no tpm-device-file is defined and hcalls will return
> > H_RESOURCE.
> 
> Wouldn't H_FUNCTION make more sense?

Yes, for this case it probably would.

Thanks for the suggestions!

> 
> > 
> > The full specification for this hypercall can be found in
> > docs/specs/ppc-spapr-uv-hcalls.txt
> > 
> > Signed-off-by: Michael Roth <address@hidden
> > ---
> >  hw/ppc/Makefile.objs     |   1 +
> >  hw/ppc/spapr.c           |  27 ++++++++
> >  hw/ppc/spapr_hcall_tpm.c | 135 +++++++++++++++++++++++++++++++++++++++
> >  hw/ppc/trace-events      |   4 ++
> >  include/hw/ppc/spapr.h   |   7 +-
> >  5 files changed, 173 insertions(+), 1 deletion(-)
> >  create mode 100644 hw/ppc/spapr_hcall_tpm.c
> > 
> > diff --git a/hw/ppc/Makefile.objs b/hw/ppc/Makefile.objs
> > index 9da93af905..5aa120cae6 100644
> > --- a/hw/ppc/Makefile.objs
> > +++ b/hw/ppc/Makefile.objs
> > @@ -5,6 +5,7 @@ obj-$(CONFIG_PSERIES) += spapr.o spapr_caps.o spapr_vio.o 
> > spapr_events.o
> >  obj-$(CONFIG_PSERIES) += spapr_hcall.o spapr_iommu.o spapr_rtas.o
> >  obj-$(CONFIG_PSERIES) += spapr_pci.o spapr_rtc.o spapr_drc.o
> >  obj-$(CONFIG_PSERIES) += spapr_cpu_core.o spapr_ovec.o spapr_irq.o
> > +obj-$(CONFIG_PSERIES) += spapr_hcall_tpm.o
> >  obj-$(CONFIG_SPAPR_RNG) +=  spapr_rng.o
> >  # IBM PowerNV
> >  obj-$(CONFIG_POWERNV) += pnv.o pnv_xscom.o pnv_core.o pnv_lpc.o pnv_psi.o 
> > pnv_occ.o pnv_bmc.o
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index 821f0d4a49..eb3421673b 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -1776,6 +1776,10 @@ static void spapr_machine_reset(MachineState 
> > *machine)
> >       */
> >      object_child_foreach_recursive(object_get_root(), spapr_reset_drcs, 
> > NULL);
> >  
> > +    if (spapr->tpm_device_file) {
> > +        spapr_hcall_tpm_reset();
> > +    }
> > +
> >      spapr_clear_pending_events(spapr);
> >  
> >      /*
> > @@ -3340,6 +3344,21 @@ static void spapr_set_host_serial(Object *obj, const 
> > char *value, Error **errp)
> >      spapr->host_serial = g_strdup(value);
> >  }
> >  
> > +static char *spapr_get_tpm_device_file(Object *obj, Error **errp)
> > +{
> > +    SpaprMachineState *spapr = SPAPR_MACHINE(obj);
> > +
> > +    return g_strdup(spapr->tpm_device_file);
> > +}
> > +
> > +static void spapr_set_tpm_device_file(Object *obj, const char *value, 
> > Error **errp)
> > +{
> > +    SpaprMachineState *spapr = SPAPR_MACHINE(obj);
> > +
> > +    g_free(spapr->tpm_device_file);
> > +    spapr->tpm_device_file = g_strdup(value);
> > +}
> > +
> >  static void spapr_instance_init(Object *obj)
> >  {
> >      SpaprMachineState *spapr = SPAPR_MACHINE(obj);
> > @@ -3396,6 +3415,14 @@ static void spapr_instance_init(Object *obj)
> >          &error_abort);
> >      object_property_set_description(obj, "host-serial",
> >          "Host serial number to advertise in guest device tree", 
> > &error_abort);
> > +    object_property_add_str(obj, "tpm-device-file",
> > +                            spapr_get_tpm_device_file,
> > +                            spapr_set_tpm_device_file, &error_abort);
> > +    object_property_set_description(obj, "tpm-device-file",
> > +                 "Specifies the path to the TPM character device file to 
> > use"
> > +                 " for TPM communication via hypercalls (usually a TPM"
> > +                 " resource manager)",
> > +                 &error_abort);
> >  }
> >  
> >  static void spapr_machine_finalizefn(Object *obj)
> > diff --git a/hw/ppc/spapr_hcall_tpm.c b/hw/ppc/spapr_hcall_tpm.c
> > new file mode 100644
> > index 0000000000..75e2b6d594
> > --- /dev/null
> > +++ b/hw/ppc/spapr_hcall_tpm.c
> > @@ -0,0 +1,135 @@
> > +/*
> > + * SPAPR TPM Hypercall
> > + *
> > + * Copyright IBM Corp. 2019
> > + *
> > + * Authors:
> > + *  Michael Roth      <address@hidden>
> > + *
> > + * This work is licensed under the terms of the GNU GPL, version 2 or 
> > later.
> > + * See the COPYING file in the top-level directory.
> > + */
> > +
> > +#include "qemu/osdep.h"
> > +#include "qemu-common.h"
> > +#include "qapi/error.h"
> > +#include "qemu/error-report.h"
> > +#include "cpu.h"
> > +#include "hw/ppc/spapr.h"
> > +#include "trace.h"
> > +
> > +#define TPM_SPAPR_BUFSIZE 4096
> > +
> > +enum {
> > +    TPM_COMM_OP_EXECUTE = 1,
> > +    TPM_COMM_OP_CLOSE_SESSION = 2,
> > +};
> > +
> > +static int tpm_devfd = -1;
> 
> A global?  Really?  You can do better.
> 
> > +
> > +static ssize_t tpm_execute(SpaprMachineState *spapr, target_ulong *args)
> > +{
> > +    uint64_t data_in = ppc64_phys_to_real(args[1]);
> > +    target_ulong data_in_size = args[2];
> > +    uint64_t data_out = ppc64_phys_to_real(args[3]);
> > +    target_ulong data_out_size = args[4];
> > +    uint8_t buf_in[TPM_SPAPR_BUFSIZE];
> > +    uint8_t buf_out[TPM_SPAPR_BUFSIZE];
> > +    ssize_t ret;
> > +
> > +    trace_spapr_tpm_execute(data_in, data_in_size, data_out, 
> > data_out_size);
> > +
> > +    if (data_in_size > TPM_SPAPR_BUFSIZE) {
> > +        error_report("invalid TPM input buffer size: " TARGET_FMT_lu "\n",
> > +                     data_in_size);
> > +        return H_P3;
> > +    }
> > +
> > +    if (data_out_size < TPM_SPAPR_BUFSIZE) {
> > +        error_report("invalid TPM output buffer size: " TARGET_FMT_lu "\n",
> > +                     data_out_size);
> > +        return H_P5;
> > +    }
> > +
> > +    if (tpm_devfd == -1) {
> > +        tpm_devfd = open(spapr->tpm_device_file, O_RDWR);
> > +        if (tpm_devfd == -1) {
> > +            error_report("failed to open TPM device %s: %d",
> > +                         spapr->tpm_device_file, errno);
> > +            return H_RESOURCE;
> > +        }
> > +    }
> > +
> > +    cpu_physical_memory_read(data_in, buf_in, data_in_size);
> > +
> > +    do {
> > +        ret = write(tpm_devfd, buf_in, data_in_size);
> > +        if (ret > 0) {
> > +            data_in_size -= ret;
> > +        }
> > +    } while ((ret >= 0 && data_in_size > 0) || (ret == -1 && errno == 
> > EINTR));
> > +
> > +    if (ret == -1) {
> > +        error_report("failed to write to TPM device %s: %d",
> > +                     spapr->tpm_device_file, errno);
> > +        return H_RESOURCE;
> > +    }
> > +
> > +    do {
> > +        ret = read(tpm_devfd, buf_out, data_out_size);
> > +    } while (ret == 0 || (ret == -1 && errno == EINTR));
> > +
> > +    if (ret == -1) {
> > +        error_report("failed to read from TPM device %s: %d",
> > +                     spapr->tpm_device_file, errno);
> > +        return H_RESOURCE;
> > +    }
> > +
> > +    cpu_physical_memory_write(data_out, buf_out, ret);
> > +    args[0] = ret;
> > +
> > +    return H_SUCCESS;
> > +}
> > +
> > +static target_ulong h_tpm_comm(PowerPCCPU *cpu,
> > +                               SpaprMachineState *spapr,
> > +                               target_ulong opcode,
> > +                               target_ulong *args)
> > +{
> > +    target_ulong op = args[0];
> > +
> > +    trace_spapr_h_tpm_comm(spapr->tpm_device_file ?: "null", op);
> > +
> > +    if (!spapr->tpm_device_file) {
> > +        error_report("TPM device not specified");
> > +        return H_RESOURCE;
> > +    }
> > +
> > +    switch (op) {
> > +        case TPM_COMM_OP_EXECUTE:
> > +            return tpm_execute(spapr, args);
> > +        case TPM_COMM_OP_CLOSE_SESSION:
> > +            if (tpm_devfd != -1) {
> > +                close(tpm_devfd);
> > +                tpm_devfd = -1;
> > +            }
> > +            return H_SUCCESS;
> > +        default:
> > +            return H_PARAMETER;
> > +    }
> > +}
> > +
> > +void spapr_hcall_tpm_reset(void)
> > +{
> > +    if (tpm_devfd != -1) {
> > +        close(tpm_devfd);
> > +        tpm_devfd = -1;
> > +    }
> > +}
> > +
> > +static void hypercall_register_types(void)
> > +{
> > +    spapr_register_hypercall(H_TPM_COMM, h_tpm_comm);
> > +}
> > +
> > +type_init(hypercall_register_types)
> > diff --git a/hw/ppc/trace-events b/hw/ppc/trace-events
> > index f76448f532..96dad767a1 100644
> > --- a/hw/ppc/trace-events
> > +++ b/hw/ppc/trace-events
> > @@ -25,6 +25,10 @@ spapr_update_dt(unsigned cb) "New blob %u bytes"
> >  spapr_update_dt_failed_size(unsigned cbold, unsigned cbnew, unsigned 
> > magic) "Old blob %u bytes, new blob %u bytes, magic 0x%x"
> >  spapr_update_dt_failed_check(unsigned cbold, unsigned cbnew, unsigned 
> > magic) "Old blob %u bytes, new blob %u bytes, magic 0x%x"
> >  
> > +# spapr_hcall_tpm.c
> > +spapr_h_tpm_comm(const char *device_path, uint64_t operation) 
> > "tpm_device_path=%s operation=0x%"PRIu64
> > +spapr_tpm_execute(uint64_t data_in, uint64_t data_in_sz, uint64_t 
> > data_out, uint64_t data_out_sz) "data_in=0x%"PRIx64", data_in_sz=%"PRIu64", 
> > data_out=0x%"PRIx64", data_out_sz=%"PRIu64
> > +
> >  # spapr_iommu.c
> >  spapr_iommu_put(uint64_t liobn, uint64_t ioba, uint64_t tce, uint64_t ret) 
> > "liobn=0x%"PRIx64" ioba=0x%"PRIx64" tce=0x%"PRIx64" ret=%"PRId64
> >  spapr_iommu_get(uint64_t liobn, uint64_t ioba, uint64_t ret, uint64_t tce) 
> > "liobn=0x%"PRIx64" ioba=0x%"PRIx64" ret=%"PRId64" tce=0x%"PRIx64
> > diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> > index 60553d32c4..7bd47575d7 100644
> > --- a/include/hw/ppc/spapr.h
> > +++ b/include/hw/ppc/spapr.h
> > @@ -198,6 +198,7 @@ struct SpaprMachineState {
> >      SpaprXive  *xive;
> >      SpaprIrq *irq;
> >      qemu_irq *qirqs;
> > +    char *tpm_device_file;
> >  
> >      bool cmd_line_caps[SPAPR_CAP_NUM];
> >      SpaprCapabilities def, eff, mig;
> > @@ -490,8 +491,9 @@ struct SpaprMachineState {
> >  #define H_INT_ESB               0x3C8
> >  #define H_INT_SYNC              0x3CC
> >  #define H_INT_RESET             0x3D0
> > +#define H_TPM_COMM              0xEF10
> >  
> > -#define MAX_HCALL_OPCODE        H_INT_RESET
> > +#define MAX_HCALL_OPCODE        H_TPM_COMM
> >  
> >  /* The hcalls above are standardized in PAPR and implemented by pHyp
> >   * as well.
> > @@ -864,6 +866,9 @@ int spapr_caps_post_migration(SpaprMachineState *spapr);
> >  
> >  void spapr_check_pagesize(SpaprMachineState *spapr, hwaddr pagesize,
> >                            Error **errp);
> > +
> > +void spapr_hcall_tpm_reset(void);
> > +
> >  /*
> >   * XIVE definitions
> >   */
> 
> -- 
> David Gibson                    | I'll have my music baroque, and my code
> david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
>                                 | _way_ _around_!
> http://www.ozlabs.org/~dgibson