Commit 0342ee76 authored by Liran Alon's avatar Liran Alon Committed by Paolo Bonzini
Browse files

hw/i386/vmport: Set EAX to -1 on failed and unsupported commands 



This is used as a signal for VMware Tools to know if a command it
attempted to invoke, failed or is unsupported. As a result, VMware Tools
will either report failure to user or fallback to another backdoor command
in attempt to perform some operation.

A few examples:
* open-vm-tools TimeSyncReadHost() function fallbacks to
CMD_GETTIMEFULL command when CMD_GETTIMEFULL_WITH_LAG
fails/unsupported.
* open-vm-tools Hostinfo_NestingSupported() function verifies
EAX != -1 to check for success.
* open-vm-tools Hostinfo_VCPUInfoBackdoor() functions checks
if reserved-bit is set to indicate command is unimplemented.

Reviewed-by: default avatarNikita Leshenko <nikita.leshchenko@oracle.com>
Signed-off-by: default avatarLiran Alon <liran.alon@oracle.com>
Message-Id: <20200312165431.82118-5-liran.alon@oracle.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent b8892129

hw/core/machine.c

+1 −0
Original line number Diff line number Diff line
@@ -44,6 +44,7 @@ GlobalProperty hw_compat_4_2[] = { 
    { "qxl-vga", "revision", "4" },

    { "fw_cfg", "acpi-mr-restore", "false" },

    { "vmport", "x-read-set-eax", "off" },

    { "vmport", "x-signal-unsupported-cmd", "off" },

};

const size_t hw_compat_4_2_len = G_N_ELEMENTS(hw_compat_4_2);

hw/i386/vmport.c

+15 −4
Original line number Diff line number Diff line
@@ -45,8 +45,11 @@ 


/* Compatibility flags for migration */

#define VMPORT_COMPAT_READ_SET_EAX_BIT              0

#define VMPORT_COMPAT_SIGNAL_UNSUPPORTED_CMD_BIT    1

#define VMPORT_COMPAT_READ_SET_EAX              \

    (1 << VMPORT_COMPAT_READ_SET_EAX_BIT)

#define VMPORT_COMPAT_SIGNAL_UNSUPPORTED_CMD    \

    (1 << VMPORT_COMPAT_SIGNAL_UNSUPPORTED_CMD_BIT)



#define VMPORT(obj) OBJECT_CHECK(VMPortState, (obj), TYPE_VMPORT)
@@ -87,17 +90,23 @@ static uint64_t vmport_ioport_read(void *opaque, hwaddr addr, 


    eax = env->regs[R_EAX];

    if (eax != VMPORT_MAGIC) {

        goto out;

        goto err;

    }



    command = env->regs[R_ECX];

    trace_vmport_command(command);

    if (command >= VMPORT_ENTRIES || !s->func[command]) {

        qemu_log_mask(LOG_UNIMP, "vmport: unknown command %x\n", command);

        goto out;

        goto err;

    }



    eax = s->func[command](s->opaque[command], addr);

    goto out;



err:

    if (s->compat_flags & VMPORT_COMPAT_SIGNAL_UNSUPPORTED_CMD) {

        eax = UINT32_MAX;

    }



out:

    /*
@@ -168,6 +177,8 @@ static Property vmport_properties[] = { 
    /* Used to enforce compatibility for migration */

    DEFINE_PROP_BIT("x-read-set-eax", VMPortState, compat_flags,

                    VMPORT_COMPAT_READ_SET_EAX_BIT, true),

    DEFINE_PROP_BIT("x-signal-unsupported-cmd", VMPortState, compat_flags,

                    VMPORT_COMPAT_SIGNAL_UNSUPPORTED_CMD_BIT, true),

    DEFINE_PROP_END_OF_LIST(),

};