The vcpu and vm mem_op ioctl implementations share some functionality.
Move argument checking and buffer allocation into functions and call
them from both implementations.
This allows code reuse in case of additional future mem_op operations.
Suggested-by: Janosch Frank <[email protected]>
Signed-off-by: Janis Schoetterl-Glausch <[email protected]>
---
arch/s390/kvm/kvm-s390.c | 80 +++++++++++++++++++++-------------------
1 file changed, 42 insertions(+), 38 deletions(-)
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index e4890e04b210..e0dfaa195949 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2764,24 +2764,44 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
return r;
}
-static bool access_key_invalid(u8 access_key)
+static int mem_op_validate_common(struct kvm_s390_mem_op *mop, u64 supported_flags)
{
- return access_key > 0xf;
+ if (mop->flags & ~supported_flags || !mop->size)
+ return -EINVAL;
+ if (mop->size > MEM_OP_MAX_SIZE)
+ return -E2BIG;
+ if (mop->flags & KVM_S390_MEMOP_F_SKEY_PROTECTION) {
+ if (mop->key > 0xf)
+ return -EINVAL;
+ } else {
+ mop->key = 0;
+ }
+ return 0;
+}
+
+static void *mem_op_alloc_buf(struct kvm_s390_mem_op *mop)
+{
+ void *buf;
+
+ if (mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY)
+ return NULL;
+ buf = vmalloc(mop->size);
+ if (!buf)
+ return ERR_PTR(-ENOMEM);
+ return buf;
}
static int kvm_s390_vm_mem_op(struct kvm *kvm, struct kvm_s390_mem_op *mop)
{
void __user *uaddr = (void __user *)mop->buf;
- u64 supported_flags;
void *tmpbuf = NULL;
int r, srcu_idx;
- supported_flags = KVM_S390_MEMOP_F_SKEY_PROTECTION
- | KVM_S390_MEMOP_F_CHECK_ONLY;
- if (mop->flags & ~supported_flags || !mop->size)
- return -EINVAL;
- if (mop->size > MEM_OP_MAX_SIZE)
- return -E2BIG;
+ r = mem_op_validate_common(mop, KVM_S390_MEMOP_F_SKEY_PROTECTION |
+ KVM_S390_MEMOP_F_CHECK_ONLY);
+ if (r)
+ return r;
+
/*
* This is technically a heuristic only, if the kvm->lock is not
* taken, it is not guaranteed that the vm is/remains non-protected.
@@ -2793,17 +2813,9 @@ static int kvm_s390_vm_mem_op(struct kvm *kvm, struct kvm_s390_mem_op *mop)
*/
if (kvm_s390_pv_get_handle(kvm))
return -EINVAL;
- if (mop->flags & KVM_S390_MEMOP_F_SKEY_PROTECTION) {
- if (access_key_invalid(mop->key))
- return -EINVAL;
- } else {
- mop->key = 0;
- }
- if (!(mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY)) {
- tmpbuf = vmalloc(mop->size);
- if (!tmpbuf)
- return -ENOMEM;
- }
+ tmpbuf = mem_op_alloc_buf(mop);
+ if (IS_ERR(tmpbuf))
+ return PTR_ERR(tmpbuf);
srcu_idx = srcu_read_lock(&kvm->srcu);
@@ -5250,28 +5262,20 @@ static long kvm_s390_vcpu_mem_op(struct kvm_vcpu *vcpu,
{
void __user *uaddr = (void __user *)mop->buf;
void *tmpbuf = NULL;
- int r = 0;
- const u64 supported_flags = KVM_S390_MEMOP_F_INJECT_EXCEPTION
- | KVM_S390_MEMOP_F_CHECK_ONLY
- | KVM_S390_MEMOP_F_SKEY_PROTECTION;
+ int r;
- if (mop->flags & ~supported_flags || mop->ar >= NUM_ACRS || !mop->size)
+ r = mem_op_validate_common(mop, KVM_S390_MEMOP_F_INJECT_EXCEPTION |
+ KVM_S390_MEMOP_F_CHECK_ONLY |
+ KVM_S390_MEMOP_F_SKEY_PROTECTION);
+ if (r)
+ return r;
+ if (mop->ar >= NUM_ACRS)
return -EINVAL;
- if (mop->size > MEM_OP_MAX_SIZE)
- return -E2BIG;
if (kvm_s390_pv_cpu_is_protected(vcpu))
return -EINVAL;
- if (mop->flags & KVM_S390_MEMOP_F_SKEY_PROTECTION) {
- if (access_key_invalid(mop->key))
- return -EINVAL;
- } else {
- mop->key = 0;
- }
- if (!(mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY)) {
- tmpbuf = vmalloc(mop->size);
- if (!tmpbuf)
- return -ENOMEM;
- }
+ tmpbuf = mem_op_alloc_buf(mop);
+ if (IS_ERR(tmpbuf))
+ return PTR_ERR(tmpbuf);
switch (mop->op) {
case KVM_S390_MEMOP_LOGICAL_READ:
--
2.34.1
On 25/01/2023 22.26, Janis Schoetterl-Glausch wrote:
> The vcpu and vm mem_op ioctl implementations share some functionality.
> Move argument checking and buffer allocation into functions and call
> them from both implementations.
> This allows code reuse in case of additional future mem_op operations.
>
> Suggested-by: Janosch Frank <[email protected]>
> Signed-off-by: Janis Schoetterl-Glausch <[email protected]>
> ---
> arch/s390/kvm/kvm-s390.c | 80 +++++++++++++++++++++-------------------
> 1 file changed, 42 insertions(+), 38 deletions(-)
>
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index e4890e04b210..e0dfaa195949 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -2764,24 +2764,44 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
> return r;
> }
>
> -static bool access_key_invalid(u8 access_key)
> +static int mem_op_validate_common(struct kvm_s390_mem_op *mop, u64 supported_flags)
> {
> - return access_key > 0xf;
> + if (mop->flags & ~supported_flags || !mop->size)
> + return -EINVAL;
> + if (mop->size > MEM_OP_MAX_SIZE)
> + return -E2BIG;
> + if (mop->flags & KVM_S390_MEMOP_F_SKEY_PROTECTION) {
> + if (mop->key > 0xf)
> + return -EINVAL;
> + } else {
> + mop->key = 0;
> + }
> + return 0;
> +}
> +
> +static void *mem_op_alloc_buf(struct kvm_s390_mem_op *mop)
> +{
> + void *buf;
> +
> + if (mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY)
> + return NULL;
> + buf = vmalloc(mop->size);
> + if (!buf)
> + return ERR_PTR(-ENOMEM);
> + return buf;
> }
>
> static int kvm_s390_vm_mem_op(struct kvm *kvm, struct kvm_s390_mem_op *mop)
> {
> void __user *uaddr = (void __user *)mop->buf;
> - u64 supported_flags;
> void *tmpbuf = NULL;
You likely can now remove the "= NULL" here, I guess?
> int r, srcu_idx;
>
> - supported_flags = KVM_S390_MEMOP_F_SKEY_PROTECTION
> - | KVM_S390_MEMOP_F_CHECK_ONLY;
> - if (mop->flags & ~supported_flags || !mop->size)
> - return -EINVAL;
> - if (mop->size > MEM_OP_MAX_SIZE)
> - return -E2BIG;
> + r = mem_op_validate_common(mop, KVM_S390_MEMOP_F_SKEY_PROTECTION |
> + KVM_S390_MEMOP_F_CHECK_ONLY);
> + if (r)
> + return r;
> +
> /*
> * This is technically a heuristic only, if the kvm->lock is not
> * taken, it is not guaranteed that the vm is/remains non-protected.
> @@ -2793,17 +2813,9 @@ static int kvm_s390_vm_mem_op(struct kvm *kvm, struct kvm_s390_mem_op *mop)
> */
> if (kvm_s390_pv_get_handle(kvm))
> return -EINVAL;
> - if (mop->flags & KVM_S390_MEMOP_F_SKEY_PROTECTION) {
> - if (access_key_invalid(mop->key))
> - return -EINVAL;
> - } else {
> - mop->key = 0;
> - }
> - if (!(mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY)) {
> - tmpbuf = vmalloc(mop->size);
> - if (!tmpbuf)
> - return -ENOMEM;
> - }
> + tmpbuf = mem_op_alloc_buf(mop);
> + if (IS_ERR(tmpbuf))
> + return PTR_ERR(tmpbuf);
>
> srcu_idx = srcu_read_lock(&kvm->srcu);
>
> @@ -5250,28 +5262,20 @@ static long kvm_s390_vcpu_mem_op(struct kvm_vcpu *vcpu,
> {
> void __user *uaddr = (void __user *)mop->buf;
> void *tmpbuf = NULL;
... and here, too.
But I have to admit that I'm also not sure whether I like the
mem_op_alloc_buf() part or not (the mem_op_validate_common() part looks fine
to me) : mem_op_alloc_buf() is a new function with 11 lines of code, and the
old spots that allocate memory were only 5 lines of code each, so you now
increased the LoC count and additionally have to fiddly with IS_ERR and
PTR_ERR which is always a little bit ugly in my eyes ... IMHO I'd rather
keep the old code here. But that's just my 0.02 €, if you think it's nicer
with mem_op_alloc_buf(), I won't insist on keeping the old code.
Thomas
> - int r = 0;
> - const u64 supported_flags = KVM_S390_MEMOP_F_INJECT_EXCEPTION
> - | KVM_S390_MEMOP_F_CHECK_ONLY
> - | KVM_S390_MEMOP_F_SKEY_PROTECTION;
> + int r;
>
> - if (mop->flags & ~supported_flags || mop->ar >= NUM_ACRS || !mop->size)
> + r = mem_op_validate_common(mop, KVM_S390_MEMOP_F_INJECT_EXCEPTION |
> + KVM_S390_MEMOP_F_CHECK_ONLY |
> + KVM_S390_MEMOP_F_SKEY_PROTECTION);
> + if (r)
> + return r;
> + if (mop->ar >= NUM_ACRS)
> return -EINVAL;
> - if (mop->size > MEM_OP_MAX_SIZE)
> - return -E2BIG;
> if (kvm_s390_pv_cpu_is_protected(vcpu))
> return -EINVAL;
> - if (mop->flags & KVM_S390_MEMOP_F_SKEY_PROTECTION) {
> - if (access_key_invalid(mop->key))
> - return -EINVAL;
> - } else {
> - mop->key = 0;
> - }
> - if (!(mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY)) {
> - tmpbuf = vmalloc(mop->size);
> - if (!tmpbuf)
> - return -ENOMEM;
> - }
> + tmpbuf = mem_op_alloc_buf(mop);
> + if (IS_ERR(tmpbuf))
> + return PTR_ERR(tmpbuf);
>
> switch (mop->op) {
> case KVM_S390_MEMOP_LOGICAL_READ:
On 1/26/23 07:48, Thomas Huth wrote:
> On 25/01/2023 22.26, Janis Schoetterl-Glausch wrote:
>> The vcpu and vm mem_op ioctl implementations share some functionality.
>> Move argument checking and buffer allocation into functions and call
>> them from both implementations.
>> This allows code reuse in case of additional future mem_op operations.
>>
>> Suggested-by: Janosch Frank <[email protected]>
>> Signed-off-by: Janis Schoetterl-Glausch <[email protected]>
>> ---
>> arch/s390/kvm/kvm-s390.c | 80 +++++++++++++++++++++-------------------
>> 1 file changed, 42 insertions(+), 38 deletions(-)
>>
>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
>> index e4890e04b210..e0dfaa195949 100644
>> --- a/arch/s390/kvm/kvm-s390.c
>> +++ b/arch/s390/kvm/kvm-s390.c
>> @@ -2764,24 +2764,44 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
>> return r;
>> }
>>
>> -static bool access_key_invalid(u8 access_key)
>> +static int mem_op_validate_common(struct kvm_s390_mem_op *mop, u64 supported_flags)
>> {
>> - return access_key > 0xf;
>> + if (mop->flags & ~supported_flags || !mop->size)
>> + return -EINVAL;
>> + if (mop->size > MEM_OP_MAX_SIZE)
>> + return -E2BIG;
>> + if (mop->flags & KVM_S390_MEMOP_F_SKEY_PROTECTION) {
>> + if (mop->key > 0xf)
>> + return -EINVAL;
>> + } else {
>> + mop->key = 0;
>> + }
>> + return 0;
>> +}
>> +
>> +static void *mem_op_alloc_buf(struct kvm_s390_mem_op *mop)
>> +{
>> + void *buf;
>> +
>> + if (mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY)
>> + return NULL;
>> + buf = vmalloc(mop->size);
>> + if (!buf)
>> + return ERR_PTR(-ENOMEM);
>> + return buf;
>> }
>>
>> static int kvm_s390_vm_mem_op(struct kvm *kvm, struct kvm_s390_mem_op *mop)
>> {
>> void __user *uaddr = (void __user *)mop->buf;
>> - u64 supported_flags;
>> void *tmpbuf = NULL;
>
> You likely can now remove the "= NULL" here, I guess?
>
>> int r, srcu_idx;
>>
>> - supported_flags = KVM_S390_MEMOP_F_SKEY_PROTECTION
>> - | KVM_S390_MEMOP_F_CHECK_ONLY;
>> - if (mop->flags & ~supported_flags || !mop->size)
>> - return -EINVAL;
>> - if (mop->size > MEM_OP_MAX_SIZE)
>> - return -E2BIG;
>> + r = mem_op_validate_common(mop, KVM_S390_MEMOP_F_SKEY_PROTECTION |
>> + KVM_S390_MEMOP_F_CHECK_ONLY);
>> + if (r)
>> + return r;
>> +
>> /*
>> * This is technically a heuristic only, if the kvm->lock is not
>> * taken, it is not guaranteed that the vm is/remains non-protected.
>> @@ -2793,17 +2813,9 @@ static int kvm_s390_vm_mem_op(struct kvm *kvm, struct kvm_s390_mem_op *mop)
>> */
>> if (kvm_s390_pv_get_handle(kvm))
>> return -EINVAL;
>> - if (mop->flags & KVM_S390_MEMOP_F_SKEY_PROTECTION) {
>> - if (access_key_invalid(mop->key))
>> - return -EINVAL;
>> - } else {
>> - mop->key = 0;
>> - }
>> - if (!(mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY)) {
>> - tmpbuf = vmalloc(mop->size);
>> - if (!tmpbuf)
>> - return -ENOMEM;
>> - }
>> + tmpbuf = mem_op_alloc_buf(mop);
>> + if (IS_ERR(tmpbuf))
>> + return PTR_ERR(tmpbuf);
>>
>> srcu_idx = srcu_read_lock(&kvm->srcu);
>>
>> @@ -5250,28 +5262,20 @@ static long kvm_s390_vcpu_mem_op(struct kvm_vcpu *vcpu,
>> {
>> void __user *uaddr = (void __user *)mop->buf;
>> void *tmpbuf = NULL;
>
> ... and here, too.
>
> But I have to admit that I'm also not sure whether I like the
> mem_op_alloc_buf() part or not (the mem_op_validate_common() part looks fine
> to me) : mem_op_alloc_buf() is a new function with 11 lines of code, and the
> old spots that allocate memory were only 5 lines of code each, so you now
> increased the LoC count and additionally have to fiddly with IS_ERR and
> PTR_ERR which is always a little bit ugly in my eyes ... IMHO I'd rather
> keep the old code here. But that's just my 0.02 €, if you think it's nicer
> with mem_op_alloc_buf(), I won't insist on keeping the old code.
>
> Thomas
>
I've done a PoC that has a **buff argument and combines the check with
the alloc.
@Nina: Any reason why this was split up?
On Thu, 2023-01-26 at 14:02 +0100, Janosch Frank wrote:
> On 1/26/23 07:48, Thomas Huth wrote:
> > On 25/01/2023 22.26, Janis Schoetterl-Glausch wrote:
> > > The vcpu and vm mem_op ioctl implementations share some functionality.
> > > Move argument checking and buffer allocation into functions and call
> > > them from both implementations.
> > > This allows code reuse in case of additional future mem_op operations.
> > >
> > > Suggested-by: Janosch Frank <[email protected]>
> > > Signed-off-by: Janis Schoetterl-Glausch <[email protected]>
> > > ---
> > > arch/s390/kvm/kvm-s390.c | 80 +++++++++++++++++++++-------------------
> > > 1 file changed, 42 insertions(+), 38 deletions(-)
> > >
> > > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> > > index e4890e04b210..e0dfaa195949 100644
> > > --- a/arch/s390/kvm/kvm-s390.c
> > > +++ b/arch/s390/kvm/kvm-s390.c
> > > @@ -2764,24 +2764,44 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
> > > return r;
> > > }
> > >
> > > -static bool access_key_invalid(u8 access_key)
> > > +static int mem_op_validate_common(struct kvm_s390_mem_op *mop, u64 supported_flags)
> > > {
> > > - return access_key > 0xf;
> > > + if (mop->flags & ~supported_flags || !mop->size)
> > > + return -EINVAL;
> > > + if (mop->size > MEM_OP_MAX_SIZE)
> > > + return -E2BIG;
> > > + if (mop->flags & KVM_S390_MEMOP_F_SKEY_PROTECTION) {
> > > + if (mop->key > 0xf)
> > > + return -EINVAL;
> > > + } else {
> > > + mop->key = 0;
> > > + }
> > > + return 0;
> > > +}
> > > +
> > > +static void *mem_op_alloc_buf(struct kvm_s390_mem_op *mop)
> > > +{
> > > + void *buf;
> > > +
> > > + if (mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY)
> > > + return NULL;
> > > + buf = vmalloc(mop->size);
> > > + if (!buf)
> > > + return ERR_PTR(-ENOMEM);
> > > + return buf;
> > > }
> > >
> > > static int kvm_s390_vm_mem_op(struct kvm *kvm, struct kvm_s390_mem_op *mop)
> > > {
> > > void __user *uaddr = (void __user *)mop->buf;
> > > - u64 supported_flags;
> > > void *tmpbuf = NULL;
> >
> > You likely can now remove the "= NULL" here, I guess?
> >
> > > int r, srcu_idx;
> > >
> > > - supported_flags = KVM_S390_MEMOP_F_SKEY_PROTECTION
> > > - | KVM_S390_MEMOP_F_CHECK_ONLY;
> > > - if (mop->flags & ~supported_flags || !mop->size)
> > > - return -EINVAL;
> > > - if (mop->size > MEM_OP_MAX_SIZE)
> > > - return -E2BIG;
> > > + r = mem_op_validate_common(mop, KVM_S390_MEMOP_F_SKEY_PROTECTION |
> > > + KVM_S390_MEMOP_F_CHECK_ONLY);
> > > + if (r)
> > > + return r;
> > > +
> > > /*
> > > * This is technically a heuristic only, if the kvm->lock is not
> > > * taken, it is not guaranteed that the vm is/remains non-protected.
> > > @@ -2793,17 +2813,9 @@ static int kvm_s390_vm_mem_op(struct kvm *kvm, struct kvm_s390_mem_op *mop)
> > > */
> > > if (kvm_s390_pv_get_handle(kvm))
> > > return -EINVAL;
> > > - if (mop->flags & KVM_S390_MEMOP_F_SKEY_PROTECTION) {
> > > - if (access_key_invalid(mop->key))
> > > - return -EINVAL;
> > > - } else {
> > > - mop->key = 0;
> > > - }
> > > - if (!(mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY)) {
> > > - tmpbuf = vmalloc(mop->size);
> > > - if (!tmpbuf)
> > > - return -ENOMEM;
> > > - }
> > > + tmpbuf = mem_op_alloc_buf(mop);
> > > + if (IS_ERR(tmpbuf))
> > > + return PTR_ERR(tmpbuf);
> > >
> > > srcu_idx = srcu_read_lock(&kvm->srcu);
> > >
> > > @@ -5250,28 +5262,20 @@ static long kvm_s390_vcpu_mem_op(struct kvm_vcpu *vcpu,
> > > {
> > > void __user *uaddr = (void __user *)mop->buf;
> > > void *tmpbuf = NULL;
> >
> > ... and here, too.
> >
> > But I have to admit that I'm also not sure whether I like the
> > mem_op_alloc_buf() part or not (the mem_op_validate_common() part looks fine
> > to me) : mem_op_alloc_buf() is a new function with 11 lines of code, and the
> > old spots that allocate memory were only 5 lines of code each, so you now
> > increased the LoC count and additionally have to fiddly with IS_ERR and
> > PTR_ERR which is always a little bit ugly in my eyes ... IMHO I'd rather
> > keep the old code here. But that's just my 0.02 €, if you think it's nicer
> > with mem_op_alloc_buf(), I won't insist on keeping the old code.
> >
> > Thomas
> >
>
> I've done a PoC that has a **buff argument and combines the check with
> the alloc.
I just didn't like that much because it felt like an unspecific memop_do_things function.
On Thu, 2023-01-26 at 07:48 +0100, Thomas Huth wrote:
> On 25/01/2023 22.26, Janis Schoetterl-Glausch wrote:
> > The vcpu and vm mem_op ioctl implementations share some functionality.
> > Move argument checking and buffer allocation into functions and call
> > them from both implementations.
> > This allows code reuse in case of additional future mem_op operations.
> >
> > Suggested-by: Janosch Frank <[email protected]>
> > Signed-off-by: Janis Schoetterl-Glausch <[email protected]>
> > ---
> > arch/s390/kvm/kvm-s390.c | 80 +++++++++++++++++++++-------------------
> > 1 file changed, 42 insertions(+), 38 deletions(-)
> >
> > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> > index e4890e04b210..e0dfaa195949 100644
> > --- a/arch/s390/kvm/kvm-s390.c
> > +++ b/arch/s390/kvm/kvm-s390.c
> > @@ -2764,24 +2764,44 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
> > return r;
> > }
> >
> > -static bool access_key_invalid(u8 access_key)
> > +static int mem_op_validate_common(struct kvm_s390_mem_op *mop, u64 supported_flags)
> > {
> > - return access_key > 0xf;
> > + if (mop->flags & ~supported_flags || !mop->size)
> > + return -EINVAL;
> > + if (mop->size > MEM_OP_MAX_SIZE)
> > + return -E2BIG;
> > + if (mop->flags & KVM_S390_MEMOP_F_SKEY_PROTECTION) {
> > + if (mop->key > 0xf)
> > + return -EINVAL;
> > + } else {
> > + mop->key = 0;
> > + }
> > + return 0;
> > +}
> > +
> > +static void *mem_op_alloc_buf(struct kvm_s390_mem_op *mop)
> > +{
> > + void *buf;
> > +
> > + if (mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY)
> > + return NULL;
> > + buf = vmalloc(mop->size);
> > + if (!buf)
> > + return ERR_PTR(-ENOMEM);
> > + return buf;
> > }
> >
> > static int kvm_s390_vm_mem_op(struct kvm *kvm, struct kvm_s390_mem_op *mop)
> > {
> > void __user *uaddr = (void __user *)mop->buf;
> > - u64 supported_flags;
> > void *tmpbuf = NULL;
>
> You likely can now remove the "= NULL" here, I guess?
Yeah, I thought about it, but wasn't sure if I like moving the line down because of
some people's insistence on reverse christmas tree.
It's entirely arbitrary in a different way, but I like the return value being the last
thing declared.
In the end I forgot to make a decision on it.
>
> > int r, srcu_idx;
> >
> > - supported_flags = KVM_S390_MEMOP_F_SKEY_PROTECTION
> > - | KVM_S390_MEMOP_F_CHECK_ONLY;
> > - if (mop->flags & ~supported_flags || !mop->size)
> > - return -EINVAL;
> > - if (mop->size > MEM_OP_MAX_SIZE)
> > - return -E2BIG;
> > + r = mem_op_validate_common(mop, KVM_S390_MEMOP_F_SKEY_PROTECTION |
> > + KVM_S390_MEMOP_F_CHECK_ONLY);
> > + if (r)
> > + return r;
> > +
> > /*
> > * This is technically a heuristic only, if the kvm->lock is not
> > * taken, it is not guaranteed that the vm is/remains non-protected.
> > @@ -2793,17 +2813,9 @@ static int kvm_s390_vm_mem_op(struct kvm *kvm, struct kvm_s390_mem_op *mop)
> > */
> > if (kvm_s390_pv_get_handle(kvm))
> > return -EINVAL;
> > - if (mop->flags & KVM_S390_MEMOP_F_SKEY_PROTECTION) {
> > - if (access_key_invalid(mop->key))
> > - return -EINVAL;
> > - } else {
> > - mop->key = 0;
> > - }
> > - if (!(mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY)) {
> > - tmpbuf = vmalloc(mop->size);
> > - if (!tmpbuf)
> > - return -ENOMEM;
> > - }
> > + tmpbuf = mem_op_alloc_buf(mop);
> > + if (IS_ERR(tmpbuf))
> > + return PTR_ERR(tmpbuf);
> >
> > srcu_idx = srcu_read_lock(&kvm->srcu);
> >
> > @@ -5250,28 +5262,20 @@ static long kvm_s390_vcpu_mem_op(struct kvm_vcpu *vcpu,
> > {
> > void __user *uaddr = (void __user *)mop->buf;
> > void *tmpbuf = NULL;
>
> ... and here, too.
>
> But I have to admit that I'm also not sure whether I like the
> mem_op_alloc_buf() part or not (the mem_op_validate_common() part looks fine
> to me) : mem_op_alloc_buf() is a new function with 11 lines of code, and the
> old spots that allocate memory were only 5 lines of code each, so you now
> increased the LoC count and additionally have to fiddly with IS_ERR and
> PTR_ERR which is always a little bit ugly in my eyes ... IMHO I'd rather
> keep the old code here. But that's just my 0.02 €, if you think it's nicer
> with mem_op_alloc_buf(), I won't insist on keeping the old code.
Yeah, that's fair.
>
> Thomas
>
>
> > - int r = 0;
> > - const u64 supported_flags = KVM_S390_MEMOP_F_INJECT_EXCEPTION
> > - | KVM_S390_MEMOP_F_CHECK_ONLY
> > - | KVM_S390_MEMOP_F_SKEY_PROTECTION;
> > + int r;
> >
> > - if (mop->flags & ~supported_flags || mop->ar >= NUM_ACRS || !mop->size)
> > + r = mem_op_validate_common(mop, KVM_S390_MEMOP_F_INJECT_EXCEPTION |
> > + KVM_S390_MEMOP_F_CHECK_ONLY |
> > + KVM_S390_MEMOP_F_SKEY_PROTECTION);
> > + if (r)
> > + return r;
> > + if (mop->ar >= NUM_ACRS)
> > return -EINVAL;
> > - if (mop->size > MEM_OP_MAX_SIZE)
> > - return -E2BIG;
> > if (kvm_s390_pv_cpu_is_protected(vcpu))
> > return -EINVAL;
> > - if (mop->flags & KVM_S390_MEMOP_F_SKEY_PROTECTION) {
> > - if (access_key_invalid(mop->key))
> > - return -EINVAL;
> > - } else {
> > - mop->key = 0;
> > - }
> > - if (!(mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY)) {
> > - tmpbuf = vmalloc(mop->size);
> > - if (!tmpbuf)
> > - return -ENOMEM;
> > - }
> > + tmpbuf = mem_op_alloc_buf(mop);
> > + if (IS_ERR(tmpbuf))
> > + return PTR_ERR(tmpbuf);
> >
> > switch (mop->op) {
> > case KVM_S390_MEMOP_LOGICAL_READ:
>