On Wed, Nov 02, 2022 at 11:19:03PM +0000,
Sean Christopherson <seanjc@xxxxxxxxxx> wrote:
> From: Chao Gao <chao.gao@xxxxxxxxx>
>
> Do compatibility checks when enabling hardware to effectively add
> compatibility checks when onlining a CPU. Abort enabling, i.e. the
> online process, if the (hotplugged) CPU is incompatible with the known
> good setup.
>
> At init time, KVM does compatibility checks to ensure that all online
> CPUs support hardware virtualization and a common set of features. But
> KVM uses hotplugged CPUs without such compatibility checks. On Intel
> CPUs, this leads to #GP if the hotplugged CPU doesn't support VMX, or
> VM-Entry failure if the hotplugged CPU doesn't support all features
> enabled by KVM.
>
> Note, this is little more than a NOP on SVM, as SVM already checks for
> full SVM support during hardware enabling.
>
> Opportunistically add a pr_err() if setup_vmcs_config() fails, and
> tweak all error messages to output which CPU failed.
>
> Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>
> Co-developed-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> ---
> arch/x86/include/asm/kvm_host.h | 2 +-
> arch/x86/kvm/svm/svm.c | 20 +++++++++++---------
> arch/x86/kvm/vmx/vmx.c | 33 +++++++++++++++++++--------------
> arch/x86/kvm/x86.c | 5 +++--
> 4 files changed, 34 insertions(+), 26 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index f223c845ed6e..c99222b71fcc 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1666,7 +1666,7 @@ struct kvm_x86_nested_ops {
> };
>
> struct kvm_x86_init_ops {
> - int (*check_processor_compatibility)(void);
> + int (*check_processor_compatibility)(int cpu);
Is this cpu argument used only for error message to include cpu number
with avoiding repeating raw_smp_processor_id() in pr_err()?
The actual check is done on the current executing cpu.
If cpu != raw_smp_processor_id(), cpu is wrong. Although the function is called
in non-preemptive context, it's a bit confusing. So voting to remove it and
to use.
Thanks,
--
Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
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