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hv: bugfix: skip invalid ffs64 return value

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ffs64() returns INVALID_BIT_INDEX (0xffffU) when it tries to deal with
zero input value. This may happen In calculate_logical_dest_mask() when
the guest tries to write some illegal destination IDs to MSI config
registers of a pt-device. The ffs64() return value is used as per_cpu
array index, and it would cause a page fault.

This patch adds protection to the per_cpu array, making this function
return zero on illegal value. As in logical destination's definition, a
zero logical designation would point to no CPU.

Fixes: 1334349f8
Tracked-On: 
Signed-off-by: Wu Zhou <wu.zhou@intel.com>
Reviewed-by: Junjie Mao <junjie.mao@intel.com>
This commit is contained in:
Wu Zhou 2023-07-14 11:36:29 +08:00 committed by acrnsi-robot
parent b38003b870
commit a9860fad05
1 changed files with 22 additions and 20 deletions

42
hypervisor/arch/x86/guest/assign.c
View File

@ -53,30 +53,32 @@ static struct acrn_vcpu *is_single_destination(struct acrn_vm *vm, const struct
static uint32_t calculate_logical_dest_mask(uint64_t pdmask)
{
uint32_t dest_cluster_id, cluster_id, logical_id_mask = 0U;
uint32_t dest_cluster_id = 0U, cluster_id, logical_id_mask = 0U;
uint64_t pcpu_mask = pdmask;
uint16_t pcpu_id;
/* Guest using Guests working in xAPIC mode may use 'Flat Model' to select an
* arbitrary list of CPUs. But as the HW is woring in x2APIC mode and can only
* use 'Cluster Model', destination mask can only be assigned to pCPUs within
* one Cluster. So some pCPUs may not be included.
* Here we use the first Cluster of all the requested pCPUs.
*/
pcpu_id = ffs64(pcpu_mask);
dest_cluster_id = per_cpu(lapic_ldr, pcpu_id) & X2APIC_LDR_CLUSTER_ID_MASK;
while (pcpu_id < MAX_PCPU_NUM) {
bitmap_clear_nolock(pcpu_id, &pcpu_mask);
cluster_id = per_cpu(lapic_ldr, pcpu_id) & X2APIC_LDR_CLUSTER_ID_MASK;
if (cluster_id == dest_cluster_id) {
logical_id_mask |= (per_cpu(lapic_ldr, pcpu_id) & X2APIC_LDR_LOGICAL_ID_MASK);
} else {
pr_warn("The cluster ID of pCPU %d is %d which differs from that (%d) of "
"the previous cores in the guest logical destination.\n"
"Ignore that pCPU in the logical destination for physical interrupts.",
pcpu_id, cluster_id >> 16U, dest_cluster_id >> 16U);
}
pcpu_id = ffs64(pcpu_mask);
if (pcpu_id < MAX_PCPU_NUM) {
/* Guests working in xAPIC mode may use 'Flat Model' to select an
* arbitrary list of CPUs. But as the HW is woring in x2APIC mode and can only
* use 'Cluster Model', destination mask can only be assigned to pCPUs within
* one Cluster. So some pCPUs may not be included.
* Here we use the first Cluster of all the requested pCPUs.
*/
dest_cluster_id = per_cpu(lapic_ldr, pcpu_id) & X2APIC_LDR_CLUSTER_ID_MASK;
do {
bitmap_clear_nolock(pcpu_id, &pcpu_mask);
cluster_id = per_cpu(lapic_ldr, pcpu_id) & X2APIC_LDR_CLUSTER_ID_MASK;
if (cluster_id == dest_cluster_id) {
logical_id_mask |= (per_cpu(lapic_ldr, pcpu_id) & X2APIC_LDR_LOGICAL_ID_MASK);
} else {
pr_warn("The cluster ID of pCPU %d is %d which differs from that (%d) of "
"the previous cores in the guest logical destination.\n"
"Ignore that pCPU in the logical destination for physical interrupts.",
pcpu_id, cluster_id >> 16U, dest_cluster_id >> 16U);
}
pcpu_id = ffs64(pcpu_mask);
} while (pcpu_id < MAX_PCPU_NUM);
}
return (dest_cluster_id | logical_id_mask);