Commit ef4cbe14 authored by Stefan Weil's avatar Stefan Weil Committed by Gleb Natapov
Browse files

kvm: Fix uninitialized cpuid_data 



This error was reported by valgrind when running qemu-system-x86_64
with kvm:

==975== Conditional jump or move depends on uninitialised value(s)
==975==    at 0x521C38: cpuid_find_entry (kvm.c:176)
==975==    by 0x5235BA: kvm_arch_init_vcpu (kvm.c:686)
==975==    by 0x4D5175: kvm_init_vcpu (kvm-all.c:267)
==975==    by 0x45035B: qemu_kvm_cpu_thread_fn (cpus.c:858)
==975==    by 0xD361E0D: start_thread (pthread_create.c:311)
==975==    by 0xD65E9EC: clone (clone.S:113)
==975==  Uninitialised value was created by a stack allocation
==975==    at 0x5226E4: kvm_arch_init_vcpu (kvm.c:446)

Instead of adding more memset calls for parts of cpuid_data, the existing
calls were removed and cpuid_data is now initialized completely in one
call.

Signed-off-by: default avatarStefan Weil <sw@weilnetz.de>
Signed-off-by: default avatarGleb Natapov <gleb@redhat.com>
parent 3a902bab

target-i386/kvm.c

+2 −7
Original line number Diff line number Diff line
@@ -456,11 +456,12 @@ int kvm_arch_init_vcpu(CPUState *cs) 
    uint32_t signature[3];

    int r;



    memset(&cpuid_data, 0, sizeof(cpuid_data));



    cpuid_i = 0;



    /* Paravirtualization CPUIDs */

    c = &cpuid_data.entries[cpuid_i++];

    memset(c, 0, sizeof(*c));

    c->function = KVM_CPUID_SIGNATURE;

    if (!hyperv_enabled(cpu)) {

        memcpy(signature, "KVMKVMKVM\0\0\0", 12);
@@ -474,7 +475,6 @@ int kvm_arch_init_vcpu(CPUState *cs) 
    c->edx = signature[2];



    c = &cpuid_data.entries[cpuid_i++];

    memset(c, 0, sizeof(*c));

    c->function = KVM_CPUID_FEATURES;

    c->eax = env->features[FEAT_KVM];
@@ -483,13 +483,11 @@ int kvm_arch_init_vcpu(CPUState *cs) 
        c->eax = signature[0];



        c = &cpuid_data.entries[cpuid_i++];

        memset(c, 0, sizeof(*c));

        c->function = HYPERV_CPUID_VERSION;

        c->eax = 0x00001bbc;

        c->ebx = 0x00060001;



        c = &cpuid_data.entries[cpuid_i++];

        memset(c, 0, sizeof(*c));

        c->function = HYPERV_CPUID_FEATURES;

        if (cpu->hyperv_relaxed_timing) {

            c->eax |= HV_X64_MSR_HYPERCALL_AVAILABLE;
@@ -500,7 +498,6 @@ int kvm_arch_init_vcpu(CPUState *cs) 
        }



        c = &cpuid_data.entries[cpuid_i++];

        memset(c, 0, sizeof(*c));

        c->function = HYPERV_CPUID_ENLIGHTMENT_INFO;

        if (cpu->hyperv_relaxed_timing) {

            c->eax |= HV_X64_RELAXED_TIMING_RECOMMENDED;
@@ -511,13 +508,11 @@ int kvm_arch_init_vcpu(CPUState *cs) 
        c->ebx = cpu->hyperv_spinlock_attempts;



        c = &cpuid_data.entries[cpuid_i++];

        memset(c, 0, sizeof(*c));

        c->function = HYPERV_CPUID_IMPLEMENT_LIMITS;

        c->eax = 0x40;

        c->ebx = 0x40;



        c = &cpuid_data.entries[cpuid_i++];

        memset(c, 0, sizeof(*c));

        c->function = KVM_CPUID_SIGNATURE_NEXT;

        memcpy(signature, "KVMKVMKVM\0\0\0", 12);

        c->eax = 0;