[PATCH v3 1/4] kvm: decode the argument for KVM_SET_USER_MEMORY_REGION ioctl command

[Dmitry V. Levin]

On Mon, Dec 04, 2017 at 08:04:49PM +0900, Masatake YAMATO wrote:
> * configure.ac (AC_CHECK_TYPES): Add struct kvm_userspace_memory_region.
> * xlat/kvm_mem_flags.in: New file.
> * kvm.c: Include print_fields.h and xlat/kvm_mem_flags.h.
> (kvm_ioctl_set_user_memory_region): New function.
> (kvm_ioctl) <KVM_SET_USER_MEMORY_REGION>: Use it.
> 
> Change in v2:
> * Use umove_or_printaddr instead of umove because umove_or_printaddr
>   performs verbose(tcp) check and prints the zero address nicely.
>   Suggested by ldv.
> 
> Change in v3:
> * Verify the availability struct kvm_userspace_memory_region.
>   Suggested by ldv.
> 
> Signed-off-by: Masatake YAMATO <yamato at redhat.com>
> ---
>  configure.ac          |  2 ++
>  kvm.c                 | 27 +++++++++++++++++++++++++++
>  xlat/kvm_mem_flags.in |  2 ++
>  3 files changed, 31 insertions(+)
>  create mode 100644 xlat/kvm_mem_flags.in
> 
> diff --git a/configure.ac b/configure.ac
> index fa451d84..dad995c4 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -541,6 +541,8 @@ AC_CHECK_TYPES([struct statfs64], [
>  
>  AC_CHECK_TYPES([struct blk_user_trace_setup],,, [#include <linux/blktrace_api.h>])
>  
> +AC_CHECK_TYPES([struct kvm_userspace_memory_region],,, [#include <linux/kvm.h>])
> +
>  AC_CHECK_HEADERS([linux/btrfs.h], [
>  	AC_CHECK_MEMBERS(m4_normalize([
>  		struct btrfs_ioctl_feature_flags.compat_flags,
> diff --git a/kvm.c b/kvm.c
> index 9e4f9978..8f68aef5 100644
> --- a/kvm.c
> +++ b/kvm.c
> @@ -32,6 +32,7 @@
>  
>  #ifdef HAVE_LINUX_KVM_H
>  # include <linux/kvm.h>
> +# include "print_fields.h"
>  
>  static int
>  kvm_ioctl_create_vcpu(struct tcb *const tcp, const kernel_ulong_t arg)
> @@ -42,12 +43,38 @@ kvm_ioctl_create_vcpu(struct tcb *const tcp, const kernel_ulong_t arg)
>  	return RVAL_IOCTL_DECODED | RVAL_FD;
>  }
>  
> +# include "xlat/kvm_mem_flags.h"
> +static int
> +kvm_ioctl_set_user_memory_region(struct tcb *const tcp, const kernel_ulong_t arg)
> +{
> +#ifdef HAVE_STRUCT_KVM_USERSPACE_MEMORY_REGION
> +	struct kvm_userspace_memory_region u_memory_region;
> +
> +	tprints(", ");
> +	if (umove_or_printaddr(tcp, arg, &u_memory_region))
> +		return RVAL_IOCTL_DECODED;
> +
> +	PRINT_FIELD_U("{", u_memory_region, slot);
> +	PRINT_FIELD_FLAGS(", ", u_memory_region, flags, kvm_mem_flags,
> +			  "KVM_MEM_???");
> +	PRINT_FIELD_X(", ", u_memory_region, guest_phys_addr);
> +	PRINT_FIELD_U(", ", u_memory_region, memory_size);
> +	PRINT_FIELD_X(", ", u_memory_region, userspace_addr);
> +
> +	return RVAL_IOCTL_DECODED;
> +#else
> +	return RVAL_DECODED;
> +#endif
> +}
> +
>  int
>  kvm_ioctl(struct tcb *const tcp, const unsigned int code, const kernel_ulong_t arg)
>  {
>  	switch (code) {
>  	case KVM_CREATE_VCPU:
>  		return kvm_ioctl_create_vcpu(tcp, arg);
> +	case KVM_SET_USER_MEMORY_REGION:
> +		return kvm_ioctl_set_user_memory_region(tcp, arg);

If HAVE_STRUCT_KVM_USERSPACE_MEMORY_REGION is not set, then
KVM_SET_USER_MEMORY_REGION is not available, too,
and it's use also has to be guarded, e.g.

# ifdef HAVE_STRUCT_KVM_USERSPACE_MEMORY_REGION
	case KVM_SET_USER_MEMORY_REGION:
	return kvm_ioctl_set_user_memory_region(tcp, arg);
# endif

This allows to move the whole definition
of kvm_ioctl_set_user_memory_region inside
HAVE_STRUCT_KVM_USERSPACE_MEMORY_REGION guard, too.


-- 
ldv
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