On 25/11/2015 16:49, Eduardo Habkost wrote:
> Instead of silently changing the number of banks in mcg_cap based
> on kvm_get_mce_cap_supported(), abort initialization if the host
> doesn't support MCE_BANKS_DEF banks.
>
> Note that MCE_BANKS_DEF was always 10 since it was introduced in
> QEMU, and Linux always returned 32 at KVM_CAP_MCE since
> KVM_CAP_MCE was introduced, so no behavior is being changed and
> the error can't be triggered by any Linux version. The point of
> the new check is to ensure we won't silently change the bank
> count if we change MCE_BANKS_DEF or make the bank count
> configurable in the future.
>
> Signed-off-by: Eduardo Habkost <ehabkost@xxxxxxxxxx>
> ---
> target-i386/kvm.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/target-i386/kvm.c b/target-i386/kvm.c
> index 2a9953b..ee7bc69 100644
> --- a/target-i386/kvm.c
> +++ b/target-i386/kvm.c
> @@ -784,11 +784,14 @@ int kvm_arch_init_vcpu(CPUState *cs)
> return ret;
> }
>
> - if (banks > MCE_BANKS_DEF) {
> - banks = MCE_BANKS_DEF;
> + if (MCE_BANKS_DEF > banks) {
> + error_report("kvm: Unsupported MCE bank count: %d > %d\n",
> + MCE_BANKS_DEF, banks);
Yoda conditions?
if (banks < MCE_BANKS_DEF) {
error_report("kvm: Unsupported MCE bank count (QEMU = %d, KVM = %d)",
MCE_BANKS_DEF, banks);
Paolo
> + return -ENOTSUP;
> }
> +
> mcg_cap &= MCE_CAP_DEF;
> - mcg_cap |= banks;
> + mcg_cap |= MCE_BANKS_DEF;
> ret = kvm_vcpu_ioctl(cs, KVM_X86_SETUP_MCE, &mcg_cap);
> if (ret < 0) {
> fprintf(stderr, "KVM_X86_SETUP_MCE: %s", strerror(-ret));
>
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