Re: [PATCH v6 03/18] s390x: protvirt: Support unpack facility

[David Hildenbrand]

On 04.03.20 12:42, Janosch Frank wrote:
> When a guest has saved a ipib of type 5 and calls diagnose308 with

s/a/an/

> subcode 10, we have to setup the protected processing environment via
> Ultravisor calls. The calls are done by KVM and are exposed via an
> API.
> 
> The following steps are necessary:
> 1. Enable protected mode for the VM (register it and its cpus with the 
> Ultravisor)
> 2. Forward the secure header to the Ultravisor (has all information on
> how to decrypt the image and VM information)
> 3. Protect image pages from the host and decrypt them
> 4. Verify the image integrity
> 
> Only after step 4 a protected VM is allowed to run.
> 
> Signed-off-by: Janosch Frank <address@hidden>
> Signed-off-by: Christian Borntraeger <address@hidden> [Changes
> to machine]
> ---
>  hw/s390x/Makefile.objs              |   1 +
>  hw/s390x/ipl.c                      |  33 +++++++++
>  hw/s390x/ipl.h                      |   2 +
>  hw/s390x/pv.c                       | 106 ++++++++++++++++++++++++++++
>  hw/s390x/pv.h                       |  34 +++++++++
>  hw/s390x/s390-virtio-ccw.c          |  91 ++++++++++++++++++++++++
>  include/hw/s390x/s390-virtio-ccw.h  |   1 +
>  target/s390x/cpu.c                  |   4 ++
>  target/s390x/cpu.h                  |   1 +
>  target/s390x/cpu_features_def.inc.h |   1 +
>  10 files changed, 274 insertions(+)
>  create mode 100644 hw/s390x/pv.c
>  create mode 100644 hw/s390x/pv.h

[...]

>  
>  #define KERN_IMAGE_START                0x010000UL
>  #define LINUX_MAGIC_ADDR                0x010008UL
> @@ -676,6 +677,38 @@ static void s390_ipl_prepare_qipl(S390CPU *cpu)
>      cpu_physical_memory_unmap(addr, len, 1, len);
>  }
>  
> +int s390_ipl_prepare_pv_header(void)
> +{
> +    S390IPLState *ipl = get_ipl_device();
> +    IPLBlockPV *ipib_pv = &ipl->iplb_pv.pv;
> +    void *hdr = g_malloc(ipib_pv->pv_header_len);
> +    int rc;
> +
> +    cpu_physical_memory_read(ipib_pv->pv_header_addr, hdr,
> +                             ipib_pv->pv_header_len);
> +    rc = s390_pv_set_sec_parms((uint64_t)hdr,
> +                          ipib_pv->pv_header_len);
> +    g_free(hdr);
> +    return rc;
> +}
> +
> +int s390_ipl_pv_unpack(void)
> +{
> +    int i, rc = 0;
> +    S390IPLState *ipl = get_ipl_device();
> +    IPLBlockPV *ipib_pv = &ipl->iplb_pv.pv;
> +
> +    for (i = 0; i < ipib_pv->num_comp; i++) {
> +        rc = s390_pv_unpack(ipib_pv->components[i].addr,
> +                            TARGET_PAGE_ALIGN(ipib_pv->components[i].size),
> +                            ipib_pv->components[i].tweak_pref);
> +        if (rc) {
> +            break;
> +        }

You can check for " && !rc" in the loop condition

> +    }
> +    return rc;
> +}
> +
>  void s390_ipl_prepare_cpu(S390CPU *cpu)
>  {
>      S390IPLState *ipl = get_ipl_device();
> diff --git a/hw/s390x/ipl.h b/hw/s390x/ipl.h
> index 04be63cee1..ad8090a02c 100644
> --- a/hw/s390x/ipl.h
> +++ b/hw/s390x/ipl.h
> @@ -105,6 +105,8 @@ typedef union IplParameterBlock IplParameterBlock;
>  int s390_ipl_set_loadparm(uint8_t *loadparm);
>  int s390_ipl_pv_check_components(IplParameterBlock *iplb);
>  void s390_ipl_update_diag308(IplParameterBlock *iplb);
> +int s390_ipl_prepare_pv_header(void);
> +int s390_ipl_pv_unpack(void);
>  void s390_ipl_prepare_cpu(S390CPU *cpu);
>  IplParameterBlock *s390_ipl_get_iplb(void);
>  IplParameterBlock *s390_ipl_get_iplb_secure(void);
> diff --git a/hw/s390x/pv.c b/hw/s390x/pv.c
> new file mode 100644
> index 0000000000..50b68b6c34
> --- /dev/null
> +++ b/hw/s390x/pv.c
> @@ -0,0 +1,106 @@
> +/*
> + * Secure execution functions
> + *
> + * Copyright IBM Corp. 2020
> + * Author(s):
> + *  Janosch Frank <address@hidden>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or (at
> + * your option) any later version. See the COPYING file in the top-level
> + * directory.
> + */
> +#include "qemu/osdep.h"
> +#include <sys/ioctl.h>
> +
> +#include <linux/kvm.h>
> +
> +#include "qemu/error-report.h"
> +#include "sysemu/kvm.h"
> +#include "pv.h"
> +
> +const char *cmd_names[] = {
> +    "VM_ENABLE",
> +    "VM_DISABLE",
> +    "VM_SET_SEC_PARAMS",
> +    "VM_UNPACK",
> +    "VM_VERIFY",
> +    "VM_PREP_RESET",
> +    "VM_UNSHARE_ALL",
> +    NULL

Is the NULL really needed? This will be somewhat error prone when we add
new PV commands. Not sure if guarding this by an access function (chack
against ARRAY_SIZE() makes sense).

> diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
> index a89cf4c129..dd39890f89 100644
> --- a/hw/s390x/s390-virtio-ccw.c
> +++ b/hw/s390x/s390-virtio-ccw.c
> @@ -41,6 +41,8 @@
>  #include "hw/qdev-properties.h"
>  #include "hw/s390x/tod.h"
>  #include "sysemu/sysemu.h"
> +#include "hw/s390x/pv.h"
> +#include <linux/kvm.h>
>  
>  S390CPU *s390_cpu_addr2state(uint16_t cpu_addr)
>  {
> @@ -238,9 +240,11 @@ static void s390_create_sclpconsole(const char *type, 
> Chardev *chardev)
>  static void ccw_init(MachineState *machine)
>  {
>      int ret;
> +    S390CcwMachineState *ms = S390_CCW_MACHINE(machine);
>      VirtualCssBus *css_bus;
>      DeviceState *dev;
>  
> +    ms->pv = false;

Should not be necessary, default is false.

>      s390_sclp_init();
>      /* init memory + setup max page size. Required for the CPU model */
>      s390_memory_init(machine->ram);
> @@ -316,10 +320,75 @@ static inline void s390_do_cpu_ipl(CPUState *cs, 
> run_on_cpu_data arg)
>      s390_cpu_set_state(S390_CPU_STATE_OPERATING, cpu);
>  }
>  
> +static void s390_machine_unprotect(S390CcwMachineState *ms)
> +{
> +    CPUState *t;
> +
> +    if (!ms->pv)
> +        return;

How can this ever happen? g_assert(ms->pv) ?

Also, i don't see this function getting called from anywhere else except
when s390_machine_protect() fails. That looks wrong. This has to be
called when going out of PV mode.


> +    s390_pv_vm_disable();
> +    CPU_FOREACH(t) {
> +        S390_CPU(t)->env.pv = false;
> +    }
> +    ms->pv = false;
> +}
> +
> +static int s390_machine_protect(S390CcwMachineState *ms)
> +{
> +    CPUState *t;
> +    int rc;
> +

g_assert(!ms->pv) ?

> +    /* Create SE VM */
> +    rc = s390_pv_vm_enable();
> +    if (rc) {
> +        return rc;
> +    }
> +
> +    CPU_FOREACH(t) {
> +        S390_CPU(t)->env.pv = true;
> +    }
> +    ms->pv = true;
> +
> +    /* Set SE header and unpack */
> +    rc = s390_ipl_prepare_pv_header();
> +    if (rc) {
> +        goto out_err;
> +    }
> +
> +    /* Decrypt image */
> +    rc = s390_ipl_pv_unpack();
> +    if (rc) {
> +        goto out_err;
> +    }
> +
> +    /* Verify integrity */
> +    rc = s390_pv_verify();
> +    if (rc) {
> +        goto out_err;
> +    }
> +    return rc;
> +
> +out_err:
> +    s390_machine_unprotect(ms);
> +    return rc;
> +}
> +
> +#define DIAG_308_RC_INVAL_FOR_PV    0x0a02
> +static void s390_machine_inject_pv_error(CPUState *cs)
> +{
> +    int r1 = (cs->kvm_run->s390_sieic.ipa & 0x00f0) >> 4;
> +    CPUS390XState *env = &S390_CPU(cs)->env;
> +
> +    /* Report that we are unable to enter protected mode */
> +    env->regs[r1 + 1] = DIAG_308_RC_INVAL_FOR_PV;
> +}
> +

[...]
>      switch (reset_type) {
>      case S390_RESET_EXTERNAL:
>      case S390_RESET_REIPL:
> @@ -353,6 +424,26 @@ static void s390_machine_reset(MachineState *machine)
>          }
>          subsystem_reset();
>          run_on_cpu(cs, s390_do_cpu_initial_reset, RUN_ON_CPU_NULL);
> +        run_on_cpu(cs, s390_do_cpu_load_normal, RUN_ON_CPU_NULL);

This does look unrelated and wrong?

> +        break;
> +    case S390_RESET_PV: /* Subcode 10 */
> +        subsystem_reset();
> +        s390_crypto_reset();
> +
> +        CPU_FOREACH(t) {
> +            if (t == cs) {
> +                continue;
> +            }
> +            run_on_cpu(t, s390_do_cpu_full_reset, RUN_ON_CPU_NULL);
> +        }
> +        run_on_cpu(cs, s390_do_cpu_reset, RUN_ON_CPU_NULL);
> +
> +        if (s390_machine_protect(ms)) {
> +            s390_machine_inject_pv_error(cs);

Ah, so it's not an actual exception. BUT: All other guest cpus were
reset, can the guest deal with that?

(run_on_cpu(cs, s390_do_cpu_reset, RUN_ON_CPU_NULL) should go after the
s390_machine_protect() I assume - the change you had in the other patch)

> +            s390_cpu_set_state(S390_CPU_STATE_OPERATING, cpu);
> +            return;
> +        }
> +
>          run_on_cpu(cs, s390_do_cpu_load_normal, RUN_ON_CPU_NULL);
>          break;
>      default:


-- 
Thanks,

David / dhildenb