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SubjectRe: [PATCH 15/16] kvm: x86: set kdump virt_disable function on initialization
Eduardo Habkost <ehabkost@redhat.com> writes:

> Finally implement the virt_disable function for kdump. It will call
> kvm_x86_ops->crash_hardware_disable(), that will disable virtualization
> extensions on the CPU if it is not disabled yet.
>
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> ---
> arch/x86/kvm/x86.c | 19 ++++++++++++++++++-
> 1 files changed, 18 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 049c6a0..9e61baf 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -40,6 +40,7 @@
> #include <asm/msr.h>
> #include <asm/desc.h>
> #include <asm/mtrr.h>
> +#include <asm/virtext.h>
>
> #define MAX_IO_MSRS 256
> #define CR0_RESERVED_BITS \
> @@ -2581,6 +2582,13 @@ int kvm_emulate_pio_string(struct kvm_vcpu *vcpu, struct
> kvm_run *run, int in,
> }
> EXPORT_SYMBOL_GPL(kvm_emulate_pio_string);
>
> +/* Called at crash time, so we can disable virtualization if needed
> + */
> +static void crash_hardware_disable(void)
> +{
> + kvm_x86_ops->crash_hardware_disable(NULL);
> +}
> +
> int kvm_arch_init(void *opaque)
> {
> int r;
> @@ -2605,9 +2613,15 @@ int kvm_arch_init(void *opaque)
>
> kvm_x86_ops = ops;
>
> + r = set_virt_disable_func(crash_hardware_disable);

Can we make this say:
set_virt_disable_func(kvm_x86_ops->crash_hardware_disable);

So we can avoid going through 2 levels of function pointers?
I find that a little scary in code that might be running
at the edge of stack overflow.

> + if (r) {
> + printk(KERN_ERR "kvm: virt_disable function already set?\n");
> + goto out_clear_ops;
> + }
> +
> r = kvm_mmu_module_init();
> if (r)
> - goto out_clear_ops;
> + goto out_clear_crash;
>
> kvm_init_msr_list();
>
> @@ -2617,6 +2631,8 @@ int kvm_arch_init(void *opaque)
> PT_DIRTY_MASK, PT64_NX_MASK, 0, 0);
> return 0;
>
> +out_clear_crash:
> + clear_virt_disable_func();
> out_clear_ops:
> kvm_x86_ops = NULL;
> out:
> @@ -2625,6 +2641,7 @@ out:
>
> void kvm_arch_exit(void)
> {
> + clear_virt_disable_func();
> kvm_x86_ops = NULL;
> kvm_mmu_module_exit();
> }
> --
> 1.5.5.GIT


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