Re: [PULL 35/38] spapr: nested: Introduce H_GUEST_[GET|SET]_STATE hcalls.

2024-03-28 Thread Harsh Prateek Bora 




On 3/28/24 20:55, Peter Maydell wrote:

On Wed, 27 Mar 2024 at 05:41, Harsh Prateek Bora  wrote:




On 3/26/24 21:32, Peter Maydell wrote:

On Tue, 12 Mar 2024 at 17:11, Nicholas Piggin  wrote:


From: Harsh Prateek Bora 

Introduce the nested PAPR hcalls:
  - H_GUEST_GET_STATE which is used to get state of a nested guest or
a guest VCPU. The value field for each element in the request is
destination to be updated to reflect current state on success.
  - H_GUEST_SET_STATE which is used to modify the state of a guest or
a guest VCPU. On success, guest (or its VCPU) state shall be
updated as per the value field for the requested element(s).

Reviewed-by: Nicholas Piggin 
Signed-off-by: Michael Neuling 
Signed-off-by: Harsh Prateek Bora 
Signed-off-by: Nicholas Piggin 


Hi; Coverity points out a problem with this code (CID 1540008, 1540009):




+static target_ulong h_guest_getset_state(PowerPCCPU *cpu,
+ SpaprMachineState *spapr,
+ target_ulong *args,
+ bool set)
+{
+target_ulong flags = args[0];
+target_ulong lpid = args[1];
+target_ulong vcpuid = args[2];
+target_ulong buf = args[3];
+target_ulong buflen = args[4];
+struct guest_state_request gsr;
+SpaprMachineStateNestedGuest *guest;
+
+guest = spapr_get_nested_guest(spapr, lpid);
+if (!guest) {
+return H_P2;
+}
+gsr.buf = buf;
+assert(buflen <= GSB_MAX_BUF_SIZE);
+gsr.len = buflen;
+gsr.flags = 0;
+if (flags & H_GUEST_GETSET_STATE_FLAG_GUEST_WIDE) {


flags is a target_ulong, which means it might only be 32 bits.
But H_GUEST_GETSET_STATE_FLAG_GUEST_WIDE has a bit set in the
upper 32 bits only. So Coverity complains about this condition
being always-zero and the body of the if being dead code.

What was the intention here?


Hi Peter,
Ideally this is intended to be running on a ppc64 where target_ulong
should be uint64_t. I guess same holds true for existing nested-hv code
as well.


Sorry, I'm afraid I misread the Coverity report here;
sorry for the confusion. The 32-vs-64 bits question is a red
herring.

What Coverity is actually pointing out is in this next bit:


+gsr.flags |= GUEST_STATE_REQUEST_GUEST_WIDE;
+}
+if (flags & !H_GUEST_GETSET_STATE_FLAG_GUEST_WIDE) {


The C operator ! is the logical-NOT operator; since
H_GUEST_GETSET_STATE_FLAG_GUEST_WIDE is a non-zero value
that means that !H_GUEST_GETSET_STATE_FLAG_GUEST_WIDE is 0;
so we're testing (flags & 0), which is always false, and this
is the if() body which is dead-code as a result.

Should this be the bitwise-NOT ~  (ie "if any flag other
than this one is set"), or should this be an else clause
to the previous if() (ie "if this flag is not set") ?


Oh, this should have been bitwise-NOT, I shall send a follow-up patch 
for the fix.


regards,
Harsh



+return H_PARAMETER; /* flag not supported yet */
+}
+
+if (set) {
+gsr.flags |= GUEST_STATE_REQUEST_SET;
+}
+return map_and_getset_state(cpu, guest, vcpuid, );
+}




thanks
-- PMM

Re: [PULL 35/38] spapr: nested: Introduce H_GUEST_[GET|SET]_STATE hcalls.

2024-03-28 Thread Peter Maydell 
On Wed, 27 Mar 2024 at 05:41, Harsh Prateek Bora  wrote:
>
>
>
> On 3/26/24 21:32, Peter Maydell wrote:
> > On Tue, 12 Mar 2024 at 17:11, Nicholas Piggin  wrote:
> >>
> >> From: Harsh Prateek Bora 
> >>
> >> Introduce the nested PAPR hcalls:
> >>  - H_GUEST_GET_STATE which is used to get state of a nested guest or
> >>a guest VCPU. The value field for each element in the request is
> >>destination to be updated to reflect current state on success.
> >>  - H_GUEST_SET_STATE which is used to modify the state of a guest or
> >>a guest VCPU. On success, guest (or its VCPU) state shall be
> >>updated as per the value field for the requested element(s).
> >>
> >> Reviewed-by: Nicholas Piggin 
> >> Signed-off-by: Michael Neuling 
> >> Signed-off-by: Harsh Prateek Bora 
> >> Signed-off-by: Nicholas Piggin 
> >
> > Hi; Coverity points out a problem with this code (CID 1540008, 1540009):
> >
> >
> >
> >> +static target_ulong h_guest_getset_state(PowerPCCPU *cpu,
> >> + SpaprMachineState *spapr,
> >> + target_ulong *args,
> >> + bool set)
> >> +{
> >> +target_ulong flags = args[0];
> >> +target_ulong lpid = args[1];
> >> +target_ulong vcpuid = args[2];
> >> +target_ulong buf = args[3];
> >> +target_ulong buflen = args[4];
> >> +struct guest_state_request gsr;
> >> +SpaprMachineStateNestedGuest *guest;
> >> +
> >> +guest = spapr_get_nested_guest(spapr, lpid);
> >> +if (!guest) {
> >> +return H_P2;
> >> +}
> >> +gsr.buf = buf;
> >> +assert(buflen <= GSB_MAX_BUF_SIZE);
> >> +gsr.len = buflen;
> >> +gsr.flags = 0;
> >> +if (flags & H_GUEST_GETSET_STATE_FLAG_GUEST_WIDE) {
> >
> > flags is a target_ulong, which means it might only be 32 bits.
> > But H_GUEST_GETSET_STATE_FLAG_GUEST_WIDE has a bit set in the
> > upper 32 bits only. So Coverity complains about this condition
> > being always-zero and the body of the if being dead code.
> >
> > What was the intention here?
>
> Hi Peter,
> Ideally this is intended to be running on a ppc64 where target_ulong
> should be uint64_t. I guess same holds true for existing nested-hv code
> as well.

Sorry, I'm afraid I misread the Coverity report here;
sorry for the confusion. The 32-vs-64 bits question is a red
herring.

What Coverity is actually pointing out is in this next bit:

> >> +gsr.flags |= GUEST_STATE_REQUEST_GUEST_WIDE;
> >> +}
> >> +if (flags & !H_GUEST_GETSET_STATE_FLAG_GUEST_WIDE) {

The C operator ! is the logical-NOT operator; since
H_GUEST_GETSET_STATE_FLAG_GUEST_WIDE is a non-zero value
that means that !H_GUEST_GETSET_STATE_FLAG_GUEST_WIDE is 0;
so we're testing (flags & 0), which is always false, and this
is the if() body which is dead-code as a result.

Should this be the bitwise-NOT ~  (ie "if any flag other
than this one is set"), or should this be an else clause
to the previous if() (ie "if this flag is not set") ?

> >> +return H_PARAMETER; /* flag not supported yet */
> >> +}
> >> +
> >> +if (set) {
> >> +gsr.flags |= GUEST_STATE_REQUEST_SET;
> >> +}
> >> +return map_and_getset_state(cpu, guest, vcpuid, );
> >> +}
> >

thanks
-- PMM

Re: [PULL 35/38] spapr: nested: Introduce H_GUEST_[GET|SET]_STATE hcalls.

2024-03-27 Thread Thomas Huth 

On 27/03/2024 06.41, Harsh Prateek Bora wrote:



On 3/26/24 21:32, Peter Maydell wrote:

On Tue, 12 Mar 2024 at 17:11, Nicholas Piggin  wrote:


From: Harsh Prateek Bora 

Introduce the nested PAPR hcalls:
 - H_GUEST_GET_STATE which is used to get state of a nested guest or
   a guest VCPU. The value field for each element in the request is
   destination to be updated to reflect current state on success.
 - H_GUEST_SET_STATE which is used to modify the state of a guest or
   a guest VCPU. On success, guest (or its VCPU) state shall be
   updated as per the value field for the requested element(s).

Reviewed-by: Nicholas Piggin 
Signed-off-by: Michael Neuling 
Signed-off-by: Harsh Prateek Bora 
Signed-off-by: Nicholas Piggin 


Hi; Coverity points out a problem with this code (CID 1540008, 1540009):




+static target_ulong h_guest_getset_state(PowerPCCPU *cpu,
+ SpaprMachineState *spapr,
+ target_ulong *args,
+ bool set)
+{
+    target_ulong flags = args[0];
+    target_ulong lpid = args[1];
+    target_ulong vcpuid = args[2];
+    target_ulong buf = args[3];
+    target_ulong buflen = args[4];
+    struct guest_state_request gsr;
+    SpaprMachineStateNestedGuest *guest;
+
+    guest = spapr_get_nested_guest(spapr, lpid);
+    if (!guest) {
+    return H_P2;
+    }
+    gsr.buf = buf;
+    assert(buflen <= GSB_MAX_BUF_SIZE);
+    gsr.len = buflen;
+    gsr.flags = 0;
+    if (flags & H_GUEST_GETSET_STATE_FLAG_GUEST_WIDE) {


flags is a target_ulong, which means it might only be 32 bits.
But H_GUEST_GETSET_STATE_FLAG_GUEST_WIDE has a bit set in the
upper 32 bits only. So Coverity complains about this condition
being always-zero and the body of the if being dead code.

What was the intention here?


Hi Peter,
Ideally this is intended to be running on a ppc64 where target_ulong
should be uint64_t. I guess same holds true for existing nested-hv code
as well.

Hi Nick,
Do you think keeping both nested APIs (i.e. entire spapr_nested.c)
within #ifdef TARGET_PPC64 would be a better choice here?


spapr_numa.c is only included with CONFIG_PSERIES in hw/ppc/meson.build, so 
that should already take care that this code is only compiled with a 64-bit 
target ... Can we somehow teach Coverity to take that into consideration?


 Thomas

Re: [PULL 35/38] spapr: nested: Introduce H_GUEST_[GET|SET]_STATE hcalls.

2024-03-26 Thread Harsh Prateek Bora 




On 3/26/24 21:32, Peter Maydell wrote:

On Tue, 12 Mar 2024 at 17:11, Nicholas Piggin  wrote:


From: Harsh Prateek Bora 

Introduce the nested PAPR hcalls:
 - H_GUEST_GET_STATE which is used to get state of a nested guest or
   a guest VCPU. The value field for each element in the request is
   destination to be updated to reflect current state on success.
 - H_GUEST_SET_STATE which is used to modify the state of a guest or
   a guest VCPU. On success, guest (or its VCPU) state shall be
   updated as per the value field for the requested element(s).

Reviewed-by: Nicholas Piggin 
Signed-off-by: Michael Neuling 
Signed-off-by: Harsh Prateek Bora 
Signed-off-by: Nicholas Piggin 


Hi; Coverity points out a problem with this code (CID 1540008, 1540009):




+static target_ulong h_guest_getset_state(PowerPCCPU *cpu,
+ SpaprMachineState *spapr,
+ target_ulong *args,
+ bool set)
+{
+target_ulong flags = args[0];
+target_ulong lpid = args[1];
+target_ulong vcpuid = args[2];
+target_ulong buf = args[3];
+target_ulong buflen = args[4];
+struct guest_state_request gsr;
+SpaprMachineStateNestedGuest *guest;
+
+guest = spapr_get_nested_guest(spapr, lpid);
+if (!guest) {
+return H_P2;
+}
+gsr.buf = buf;
+assert(buflen <= GSB_MAX_BUF_SIZE);
+gsr.len = buflen;
+gsr.flags = 0;
+if (flags & H_GUEST_GETSET_STATE_FLAG_GUEST_WIDE) {


flags is a target_ulong, which means it might only be 32 bits.
But H_GUEST_GETSET_STATE_FLAG_GUEST_WIDE has a bit set in the
upper 32 bits only. So Coverity complains about this condition
being always-zero and the body of the if being dead code.

What was the intention here?


Hi Peter,
Ideally this is intended to be running on a ppc64 where target_ulong
should be uint64_t. I guess same holds true for existing nested-hv code
as well.

Hi Nick,
Do you think keeping both nested APIs (i.e. entire spapr_nested.c)
within #ifdef TARGET_PPC64 would be a better choice here?

regards,
Harsh




+gsr.flags |= GUEST_STATE_REQUEST_GUEST_WIDE;
+}
+if (flags & !H_GUEST_GETSET_STATE_FLAG_GUEST_WIDE) {
+return H_PARAMETER; /* flag not supported yet */
+}
+
+if (set) {
+gsr.flags |= GUEST_STATE_REQUEST_SET;
+}
+return map_and_getset_state(cpu, guest, vcpuid, );
+}


thanks
-- PMM

Re: [PULL 35/38] spapr: nested: Introduce H_GUEST_[GET|SET]_STATE hcalls.

2024-03-26 Thread Peter Maydell 
On Tue, 12 Mar 2024 at 17:11, Nicholas Piggin  wrote:
>
> From: Harsh Prateek Bora 
>
> Introduce the nested PAPR hcalls:
> - H_GUEST_GET_STATE which is used to get state of a nested guest or
>   a guest VCPU. The value field for each element in the request is
>   destination to be updated to reflect current state on success.
> - H_GUEST_SET_STATE which is used to modify the state of a guest or
>   a guest VCPU. On success, guest (or its VCPU) state shall be
>   updated as per the value field for the requested element(s).
>
> Reviewed-by: Nicholas Piggin 
> Signed-off-by: Michael Neuling 
> Signed-off-by: Harsh Prateek Bora 
> Signed-off-by: Nicholas Piggin 

Hi; Coverity points out a problem with this code (CID 1540008, 1540009):



> +static target_ulong h_guest_getset_state(PowerPCCPU *cpu,
> + SpaprMachineState *spapr,
> + target_ulong *args,
> + bool set)
> +{
> +target_ulong flags = args[0];
> +target_ulong lpid = args[1];
> +target_ulong vcpuid = args[2];
> +target_ulong buf = args[3];
> +target_ulong buflen = args[4];
> +struct guest_state_request gsr;
> +SpaprMachineStateNestedGuest *guest;
> +
> +guest = spapr_get_nested_guest(spapr, lpid);
> +if (!guest) {
> +return H_P2;
> +}
> +gsr.buf = buf;
> +assert(buflen <= GSB_MAX_BUF_SIZE);
> +gsr.len = buflen;
> +gsr.flags = 0;
> +if (flags & H_GUEST_GETSET_STATE_FLAG_GUEST_WIDE) {

flags is a target_ulong, which means it might only be 32 bits.
But H_GUEST_GETSET_STATE_FLAG_GUEST_WIDE has a bit set in the
upper 32 bits only. So Coverity complains about this condition
being always-zero and the body of the if being dead code.

What was the intention here?

> +gsr.flags |= GUEST_STATE_REQUEST_GUEST_WIDE;
> +}
> +if (flags & !H_GUEST_GETSET_STATE_FLAG_GUEST_WIDE) {
> +return H_PARAMETER; /* flag not supported yet */
> +}
> +
> +if (set) {
> +gsr.flags |= GUEST_STATE_REQUEST_SET;
> +}
> +return map_and_getset_state(cpu, guest, vcpuid, );
> +}

thanks
-- PMM