Re: [PATCH 06/15] s390x: protvirt: Support unpack facility

[Thomas Huth <thuth@redhat.com>]

On 20/11/2019 12.43, Janosch Frank wrote:
> When a guest has saved a ipib of type 5 and call diagnose308 with
> 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. Create a VM (register it with the Ultravisor)
> 2. Create secure CPUs for all of our current cpus
> 3. Forward the secure header to the Ultravisor (has all information on
> how to decrypt the image and VM information)
> 4. Protect image pages from the host and decrypt them
> 5. Verify the image integrity
> 
> Only after step 5 a protected VM is allowed to run.
> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> ---
[...]
> diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
> index a077926f36..50501fcd27 100644
> --- a/hw/s390x/ipl.c
> +++ b/hw/s390x/ipl.c
> @@ -33,6 +33,7 @@
>  #include "qemu/cutils.h"
>  #include "qemu/option.h"
>  #include "exec/exec-all.h"
> +#include "pv.h"
>  
>  #define KERN_IMAGE_START                0x010000UL
>  #define LINUX_MAGIC_ADDR                0x010008UL
> @@ -668,6 +669,38 @@ static void s390_ipl_prepare_qipl(S390CPU *cpu)
>      cpu_physical_memory_unmap(addr, len, 1, len);
>  }
>  
> +int s390_ipl_prepare_pv_header(void)
> +{
> +    int rc;
> +    IplParameterBlock *iplb = s390_ipl_get_iplb_secure();
> +    IPLBlockPV *ipib_pv = &iplb->pv;
> +    void *hdr = g_malloc(ipib_pv->pv_header_len);
> +
> +    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;
> +    IplParameterBlock *iplb = s390_ipl_get_iplb_secure();
> +    IPLBlockPV *ipib_pv = &iplb->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) {
> +            return rc;
> +        }
> +    }
> +    return rc;
> +}

For both functions, s390_ipl_prepare_pv_header() and
s390_ipl_pv_unpack(), you're ignoring the return code at the calling
site, so errors go completely unnoticed. I suggest to either do an
error_report() here or at the calling site...

> diff --git a/hw/s390x/pv.c b/hw/s390x/pv.c
> new file mode 100644
> index 0000000000..0218070322
> --- /dev/null
> +++ b/hw/s390x/pv.c
> @@ -0,0 +1,118 @@
> +/*
> + * Secure execution functions
> + *
> + * Copyright IBM Corp. 2019
> + * Author(s):
> + *  Janosch Frank <frankja@linux.ibm.com>
> + *
> + * 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"
> +
> +static int s390_pv_cmd(uint32_t cmd, void *data)
> +{
> +    int rc;
> +    struct kvm_pv_cmd pv_cmd = {
> +        .cmd = cmd,
> +        .data = (uint64_t)data,
> +    };
> +
> +    rc = kvm_vm_ioctl(kvm_state, KVM_S390_PV_COMMAND, &pv_cmd);
> +    if (rc) {
> +        error_report("KVM PV command failed cmd: %d rc: %d", cmd, rc);
> +        exit(1);
> +    }
> +    return rc;
> +}
> +
> +static int s390_pv_cmd_vcpu(CPUState *cs, uint32_t cmd, void *data)
> +{
> +    int rc;
> +    struct kvm_pv_cmd pv_cmd = {
> +        .cmd = cmd,
> +        .data = (uint64_t)data,
> +    };
> +
> +    rc = kvm_vcpu_ioctl(cs, KVM_S390_PV_COMMAND_VCPU, &pv_cmd);
> +    if (rc) {
> +        error_report("KVM PV VCPU command failed cmd: %d rc: %d", cmd, rc);
> +        exit(1);
> +    }
> +    return rc;
> +}

... or even better, since these functions exit on error anyway, make
these functions and all the others "void" instead?

 Thomas