From: Harsh Prateek Bora <harshpb@linux.ibm.com>
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 <npiggin@gmail.com>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
hw/ppc/spapr_nested.c | 268 ++++++++++++++++++++++++++++++++++
include/hw/ppc/spapr.h | 3 +
include/hw/ppc/spapr_nested.h | 23 +++
3 files changed, 294 insertions(+)
diff --git a/hw/ppc/spapr_nested.c b/hw/ppc/spapr_nested.c
index cd7fa90350..cea282926f 100644
--- a/hw/ppc/spapr_nested.c
+++ b/hw/ppc/spapr_nested.c
@@ -1029,6 +1029,140 @@ void spapr_nested_gsb_init(void)
}
}
+static struct guest_state_element *guest_state_element_next(
+ struct guest_state_element *element,
+ int64_t *len,
+ int64_t *num_elements)
+{
+ uint16_t size;
+
+ /* size is of element->value[] only. Not whole guest_state_element */
+ size = be16_to_cpu(element->size);
+
+ if (len) {
+ *len -= size + offsetof(struct guest_state_element, value);
+ }
+
+ if (num_elements) {
+ *num_elements -= 1;
+ }
+
+ return (struct guest_state_element *)(element->value + size);
+}
+
+static
+struct guest_state_element_type *guest_state_element_type_find(uint16_t id)
+{
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(guest_state_element_types); i++)
+ if (id == guest_state_element_types[i].id) {
+ return &guest_state_element_types[i];
+ }
+
+ return NULL;
+}
+
+static void log_element(struct guest_state_element *element,
+ struct guest_state_request *gsr)
+{
+ qemu_log_mask(LOG_GUEST_ERROR, "h_guest_%s_state id:0x%04x size:0x%04x",
+ gsr->flags & GUEST_STATE_REQUEST_SET ? "set" : "get",
+ be16_to_cpu(element->id), be16_to_cpu(element->size));
+ qemu_log_mask(LOG_GUEST_ERROR, "buf:0x%016"PRIx64" ...\n",
+ be64_to_cpu(*(uint64_t *)element->value));
+}
+
+static bool guest_state_request_check(struct guest_state_request *gsr)
+{
+ int64_t num_elements, len = gsr->len;
+ struct guest_state_buffer *gsb = gsr->gsb;
+ struct guest_state_element *element;
+ struct guest_state_element_type *type;
+ uint16_t id, size;
+
+ /* gsb->num_elements = 0 == 32 bits long */
+ assert(len >= 4);
+
+ num_elements = be32_to_cpu(gsb->num_elements);
+ element = gsb->elements;
+ len -= sizeof(gsb->num_elements);
+
+ /* Walk the buffer to validate the length */
+ while (num_elements) {
+
+ id = be16_to_cpu(element->id);
+ size = be16_to_cpu(element->size);
+
+ if (false) {
+ log_element(element, gsr);
+ }
+ /* buffer size too small */
+ if (len < 0) {
+ return false;
+ }
+
+ type = guest_state_element_type_find(id);
+ if (!type) {
+ qemu_log_mask(LOG_GUEST_ERROR, "Element ID %04x unknown\n", id);
+ log_element(element, gsr);
+ return false;
+ }
+
+ if (id == GSB_HV_VCPU_IGNORED_ID) {
+ goto next_element;
+ }
+
+ if (size != type->size) {
+ qemu_log_mask(LOG_GUEST_ERROR, "Size mismatch. Element ID:%04x."
+ "Size Exp:%i Got:%i\n", id, type->size, size);
+ log_element(element, gsr);
+ return false;
+ }
+
+ if ((type->flags & GUEST_STATE_ELEMENT_TYPE_FLAG_READ_ONLY) &&
+ (gsr->flags & GUEST_STATE_REQUEST_SET)) {
+ qemu_log_mask(LOG_GUEST_ERROR, "Trying to set a read-only Element "
+ "ID:%04x.\n", id);
+ return false;
+ }
+
+ if (type->flags & GUEST_STATE_ELEMENT_TYPE_FLAG_GUEST_WIDE) {
+ /* guest wide element type */
+ if (!(gsr->flags & GUEST_STATE_REQUEST_GUEST_WIDE)) {
+ qemu_log_mask(LOG_GUEST_ERROR, "trying to set a guest wide "
+ "Element ID:%04x.\n", id);
+ return false;
+ }
+ } else {
+ /* thread wide element type */
+ if (gsr->flags & GUEST_STATE_REQUEST_GUEST_WIDE) {
+ qemu_log_mask(LOG_GUEST_ERROR, "trying to set a thread wide "
+ "Element ID:%04x.\n", id);
+ return false;
+ }
+ }
+next_element:
+ element = guest_state_element_next(element, &len, &num_elements);
+
+ }
+ return true;
+}
+
+static bool is_gsr_invalid(struct guest_state_request *gsr,
+ struct guest_state_element *element,
+ struct guest_state_element_type *type)
+{
+ if ((gsr->flags & GUEST_STATE_REQUEST_SET) &&
+ (*(uint64_t *)(element->value) & ~(type->mask))) {
+ log_element(element, gsr);
+ qemu_log_mask(LOG_GUEST_ERROR, "L1 can't set reserved bits "
+ "(allowed mask: 0x%08"PRIx64")\n", type->mask);
+ return true;
+ }
+ return false;
+}
+
static target_ulong h_guest_get_capabilities(PowerPCCPU *cpu,
SpaprMachineState *spapr,
target_ulong opcode,
@@ -1264,6 +1398,136 @@ static target_ulong h_guest_create_vcpu(PowerPCCPU *cpu,
return H_SUCCESS;
}
+static target_ulong getset_state(SpaprMachineStateNestedGuest *guest,
+ uint64_t vcpuid,
+ struct guest_state_request *gsr)
+{
+ void *ptr;
+ uint16_t id;
+ struct guest_state_element *element;
+ struct guest_state_element_type *type;
+ int64_t lenleft, num_elements;
+
+ lenleft = gsr->len;
+
+ if (!guest_state_request_check(gsr)) {
+ return H_P3;
+ }
+
+ num_elements = be32_to_cpu(gsr->gsb->num_elements);
+ element = gsr->gsb->elements;
+ /* Process the elements */
+ while (num_elements) {
+ type = NULL;
+ /* log_element(element, gsr); */
+
+ id = be16_to_cpu(element->id);
+ if (id == GSB_HV_VCPU_IGNORED_ID) {
+ goto next_element;
+ }
+
+ type = guest_state_element_type_find(id);
+ assert(type);
+
+ /* Get pointer to guest data to get/set */
+ if (type->location && type->copy) {
+ ptr = type->location(guest, vcpuid);
+ assert(ptr);
+ if (!~(type->mask) && is_gsr_invalid(gsr, element, type)) {
+ return H_INVALID_ELEMENT_VALUE;
+ }
+ type->copy(ptr + type->offset, element->value,
+ gsr->flags & GUEST_STATE_REQUEST_SET ? true : false);
+ }
+
+next_element:
+ element = guest_state_element_next(element, &lenleft, &num_elements);
+ }
+
+ return H_SUCCESS;
+}
+
+static target_ulong map_and_getset_state(PowerPCCPU *cpu,
+ SpaprMachineStateNestedGuest *guest,
+ uint64_t vcpuid,
+ struct guest_state_request *gsr)
+{
+ target_ulong rc;
+ int64_t len;
+ bool is_write;
+
+ len = gsr->len;
+ /* only get_state would require write access to the provided buffer */
+ is_write = (gsr->flags & GUEST_STATE_REQUEST_SET) ? false : true;
+ gsr->gsb = address_space_map(CPU(cpu)->as, gsr->buf, (uint64_t *)&len,
+ is_write, MEMTXATTRS_UNSPECIFIED);
+ if (!gsr->gsb) {
+ rc = H_P3;
+ goto out1;
+ }
+
+ if (len != gsr->len) {
+ rc = H_P3;
+ goto out1;
+ }
+
+ rc = getset_state(guest, vcpuid, gsr);
+
+out1:
+ address_space_unmap(CPU(cpu)->as, gsr->gsb, len, is_write, len);
+ return rc;
+}
+
+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) {
+ 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, &gsr);
+}
+
+static target_ulong h_guest_set_state(PowerPCCPU *cpu,
+ SpaprMachineState *spapr,
+ target_ulong opcode,
+ target_ulong *args)
+{
+ return h_guest_getset_state(cpu, spapr, args, true);
+}
+
+static target_ulong h_guest_get_state(PowerPCCPU *cpu,
+ SpaprMachineState *spapr,
+ target_ulong opcode,
+ target_ulong *args)
+{
+ return h_guest_getset_state(cpu, spapr, args, false);
+}
+
void spapr_register_nested_hv(void)
{
spapr_register_hypercall(KVMPPC_H_SET_PARTITION_TABLE, h_set_ptbl);
@@ -1289,6 +1553,8 @@ void spapr_register_nested_papr(void)
spapr_register_hypercall(H_GUEST_CREATE, h_guest_create);
spapr_register_hypercall(H_GUEST_DELETE, h_guest_delete);
spapr_register_hypercall(H_GUEST_CREATE_VCPU, h_guest_create_vcpu);
+ spapr_register_hypercall(H_GUEST_SET_STATE, h_guest_set_state);
+ spapr_register_hypercall(H_GUEST_GET_STATE, h_guest_get_state);
}
void spapr_unregister_nested_papr(void)
@@ -1298,6 +1564,8 @@ void spapr_unregister_nested_papr(void)
spapr_unregister_hypercall(H_GUEST_CREATE);
spapr_unregister_hypercall(H_GUEST_DELETE);
spapr_unregister_hypercall(H_GUEST_CREATE_VCPU);
+ spapr_unregister_hypercall(H_GUEST_SET_STATE);
+ spapr_unregister_hypercall(H_GUEST_GET_STATE);
}
#else
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 070135793a..6223873641 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -366,6 +366,7 @@ struct SpaprMachineState {
#define H_OVERLAP -68
#define H_STATE -75
#define H_IN_USE -77
+#define H_INVALID_ELEMENT_VALUE -81
#define H_UNSUPPORTED_FLAG -256
#define H_MULTI_THREADS_ACTIVE -9005
@@ -589,6 +590,8 @@ struct SpaprMachineState {
#define H_GUEST_SET_CAPABILITIES 0x464
#define H_GUEST_CREATE 0x470
#define H_GUEST_CREATE_VCPU 0x474
+#define H_GUEST_GET_STATE 0x478
+#define H_GUEST_SET_STATE 0x47C
#define H_GUEST_DELETE 0x488
#define MAX_HCALL_OPCODE H_GUEST_DELETE
diff --git a/include/hw/ppc/spapr_nested.h b/include/hw/ppc/spapr_nested.h
index 3da02df7bb..bf9b258c29 100644
--- a/include/hw/ppc/spapr_nested.h
+++ b/include/hw/ppc/spapr_nested.h
@@ -224,6 +224,10 @@ typedef struct SpaprMachineStateNestedGuest {
#define HVMASK_MSR 0xEBFFFFFFFFBFEFFF
#define HVMASK_HDEXCR 0x00000000FFFFFFFF
#define HVMASK_TB_OFFSET 0x000000FFFFFFFFFF
+#define GSB_MAX_BUF_SIZE (1024 * 1024)
+#define H_GUEST_GETSET_STATE_FLAG_GUEST_WIDE 0x8000000000000000
+#define GUEST_STATE_REQUEST_GUEST_WIDE 0x1
+#define GUEST_STATE_REQUEST_SET 0x2
/*
* As per ISA v3.1B, following bits are reserved:
@@ -322,6 +326,25 @@ typedef struct SpaprMachineStateNestedGuest {
#define GSE_ENV_DWM(i, f, m) \
GUEST_STATE_ELEMENT_MSK(i, 8, f, copy_state_8to8, m)
+struct guest_state_element {
+ uint16_t id;
+ uint16_t size;
+ uint8_t value[];
+} QEMU_PACKED;
+
+struct guest_state_buffer {
+ uint32_t num_elements;
+ struct guest_state_element elements[];
+} QEMU_PACKED;
+
+/* Actual buffer plus some metadata about the request */
+struct guest_state_request {
+ struct guest_state_buffer *gsb;
+ int64_t buf;
+ int64_t len;
+ uint16_t flags;
+};
+
/*
* Register state for entering a nested guest with H_ENTER_NESTED.
* New member must be added at the end.
--
2.42.0On Tue, 12 Mar 2024 at 17:11, Nicholas Piggin <npiggin@gmail.com> wrote:
>
> From: Harsh Prateek Bora <harshpb@linux.ibm.com>
>
> 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 <npiggin@gmail.com>
> Signed-off-by: Michael Neuling <mikey@neuling.org>
> Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
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, &gsr);
> +}
thanks
-- PMM
On 3/26/24 21:32, Peter Maydell wrote:
> On Tue, 12 Mar 2024 at 17:11, Nicholas Piggin <npiggin@gmail.com> wrote:
>>
>> From: Harsh Prateek Bora <harshpb@linux.ibm.com>
>>
>> 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 <npiggin@gmail.com>
>> Signed-off-by: Michael Neuling <mikey@neuling.org>
>> Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
>> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
>
> 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, &gsr);
>> +}
>
> thanks
> -- PMM
On Wed, 27 Mar 2024 at 05:41, Harsh Prateek Bora <harshpb@linux.ibm.com> wrote:
>
>
>
> On 3/26/24 21:32, Peter Maydell wrote:
> > On Tue, 12 Mar 2024 at 17:11, Nicholas Piggin <npiggin@gmail.com> wrote:
> >>
> >> From: Harsh Prateek Bora <harshpb@linux.ibm.com>
> >>
> >> 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 <npiggin@gmail.com>
> >> Signed-off-by: Michael Neuling <mikey@neuling.org>
> >> Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
> >> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> >
> > 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, &gsr);
> >> +}
> >
thanks
-- PMM
On 3/28/24 20:55, Peter Maydell wrote:
> On Wed, 27 Mar 2024 at 05:41, Harsh Prateek Bora <harshpb@linux.ibm.com> wrote:
>>
>>
>>
>> On 3/26/24 21:32, Peter Maydell wrote:
>>> On Tue, 12 Mar 2024 at 17:11, Nicholas Piggin <npiggin@gmail.com> wrote:
>>>>
>>>> From: Harsh Prateek Bora <harshpb@linux.ibm.com>
>>>>
>>>> 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 <npiggin@gmail.com>
>>>> Signed-off-by: Michael Neuling <mikey@neuling.org>
>>>> Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
>>>> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
>>>
>>> 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, &gsr);
>>>> +}
>>>
>
> thanks
> -- PMM
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 <npiggin@gmail.com> wrote:
>>>
>>> From: Harsh Prateek Bora <harshpb@linux.ibm.com>
>>>
>>> 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 <npiggin@gmail.com>
>>> Signed-off-by: Michael Neuling <mikey@neuling.org>
>>> Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
>>> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
>>
>> 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
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