On Fri, Oct 28, 2022, Paolo Bonzini wrote:
> Registers are reachable through vcpu_vmx, no need to pass
> a separate pointer to the regs[] array.
>
> No functional change intended.
>
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> ---
> arch/x86/kernel/asm-offsets.c | 1 +
> arch/x86/kvm/vmx/nested.c | 3 +-
> arch/x86/kvm/vmx/vmenter.S | 58 +++++++++++++++--------------------
> arch/x86/kvm/vmx/vmx.c | 3 +-
> arch/x86/kvm/vmx/vmx.h | 3 +-
> 5 files changed, 29 insertions(+), 39 deletions(-)
>
> diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c
> index cb50589a7102..90da275ad223 100644
> --- a/arch/x86/kernel/asm-offsets.c
> +++ b/arch/x86/kernel/asm-offsets.c
> @@ -111,6 +111,7 @@ static void __used common(void)
>
> if (IS_ENABLED(CONFIG_KVM_INTEL)) {
> BLANK();
> + OFFSET(VMX_vcpu_arch_regs, vcpu_vmx, vcpu.arch.regs);
Is there an asm-offsets-like solution that doesn't require exposing vcpu_vmx
outside of KVM? We (Google) want to explore loading multiple instances of KVM,
i.e. loading multiple versions of kvm.ko at the same time, to allow intra-host
migration between versions of KVM to upgrade/rollback KVM without changing the
kernel (RFC coming soon-ish). IIRC, asm-offsets is the only place where I haven't
been able to figure out a simple way to avoid exposing KVM's internal structures
outside of KVM (so that the structures can change across KVM instances without
breaking kernel code).
