github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-06-04 12:35:52 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

iommu/amd: KVM: SVM: Set pCPU info in IRTE when setting vCPU affinity

Browse Source 
Now that setting vCPU affinity is guarded with ir_list_lock, i.e. now that
avic_physical_id_entry can be safely accessed, set the pCPU info
straight-away when setting vCPU affinity.  Putting the IRTE into posted
mode, and then immediately updating the IRTE a second time if the target
vCPU is running is wasteful and confusing.

This also fixes a flaw where a posted IRQ that arrives between putting
the IRTE into guest_mode and setting the correct destination could cause
the IOMMU to ring the doorbell on the wrong pCPU.

Link: https://lore.kernel.org/r/20250611224604.313496-44-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2025-06-11 15:45:45 -07:00
parent 0b2b541fa3
commit f965255dc5
4 changed files with 21 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/x86/include/asm/irq_remapping.h
View File

@ -35,6 +35,7 @@ struct amd_iommu_pi_data {
u64 vapic_addr; /* Physical address of the vCPU's vAPIC. */
u32 ga_tag;
u32 vector; /* Guest vector of the interrupt */
int cpu;
bool is_guest_mode;
void *ir_data;
};

26
arch/x86/kvm/svm/avic.c
View File

@ -727,6 +727,7 @@ void avic_apicv_post_state_restore(struct kvm_vcpu *vcpu)
static int avic_set_pi_irte_mode(struct kvm_vcpu *vcpu, bool activate)
{
int apic_id = kvm_cpu_get_apicid(vcpu->cpu);
int ret = 0;
unsigned long flags;
struct vcpu_svm *svm = to_svm(vcpu);
@ -746,7 +747,7 @@ static int avic_set_pi_irte_mode(struct kvm_vcpu *vcpu, bool activate)
list_for_each_entry(irqfd, &svm->ir_list, vcpu_list) {
if (activate)
ret = amd_iommu_activate_guest_mode(irqfd->irq_bypass_data);
ret = amd_iommu_activate_guest_mode(irqfd->irq_bypass_data, apic_id);
else
ret = amd_iommu_deactivate_guest_mode(irqfd->irq_bypass_data);
if (ret)
@ -810,6 +811,18 @@ int avic_pi_update_irte(struct kvm_kernel_irqfd *irqfd, struct kvm *kvm,
*/
guard(spinlock_irqsave)(&svm->ir_list_lock);
/*
* Update the target pCPU for IOMMU doorbells if the vCPU is
* running. If the vCPU is NOT running, i.e. is blocking or
* scheduled out, KVM will update the pCPU info when the vCPU
* is awakened and/or scheduled in. See also avic_vcpu_load().
*/
entry = svm->avic_physical_id_entry;
if (entry & AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK)
pi_data.cpu = entry & AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK;
else
pi_data.cpu = -1;
ret = irq_set_vcpu_affinity(host_irq, &pi_data);
if (ret)
return ret;
@ -824,17 +837,6 @@ int avic_pi_update_irte(struct kvm_kernel_irqfd *irqfd, struct kvm *kvm,
return -EIO;
}
/*
* Update the target pCPU for IOMMU doorbells if the vCPU is
* running. If the vCPU is NOT running, i.e. is blocking or
* scheduled out, KVM will update the pCPU info when the vCPU
* is awakened and/or scheduled in. See also avic_vcpu_load().
*/
entry = svm->avic_physical_id_entry;
if (entry & AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK)
amd_iommu_update_ga(entry & AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK,
pi_data.ir_data);
irqfd->irq_bypass_data = pi_data.ir_data;
list_add(&irqfd->vcpu_list, &svm->ir_list);
return 0;

6
drivers/iommu/amd/iommu.c
View File

@ -3850,7 +3850,7 @@ int amd_iommu_update_ga(int cpu, void *data)
}
EXPORT_SYMBOL(amd_iommu_update_ga);
int amd_iommu_activate_guest_mode(void *data)
int amd_iommu_activate_guest_mode(void *data, int cpu)
{
struct amd_ir_data *ir_data = (struct amd_ir_data *)data;
struct irte_ga *entry = (struct irte_ga *) ir_data->entry;
@ -3871,6 +3871,8 @@ int amd_iommu_activate_guest_mode(void *data)
entry->hi.fields.vector = ir_data->ga_vector;
entry->lo.fields_vapic.ga_tag = ir_data->ga_tag;
__amd_iommu_update_ga(entry, cpu);
return modify_irte_ga(ir_data->iommu, ir_data->irq_2_irte.devid,
ir_data->irq_2_irte.index, entry);
}
@ -3937,7 +3939,7 @@ static int amd_ir_set_vcpu_affinity(struct irq_data *data, void *info)
ir_data->ga_root_ptr = (pi_data->vapic_addr >> 12);
ir_data->ga_vector = pi_data->vector;
ir_data->ga_tag = pi_data->ga_tag;
ret = amd_iommu_activate_guest_mode(ir_data);
ret = amd_iommu_activate_guest_mode(ir_data, pi_data->cpu);
} else {
ret = amd_iommu_deactivate_guest_mode(ir_data);
}

4
include/linux/amd-iommu.h
View File

@ -32,7 +32,7 @@ extern int amd_iommu_register_ga_log_notifier(int (*notifier)(u32));
extern int amd_iommu_update_ga(int cpu, void *data);
extern int amd_iommu_activate_guest_mode(void *data);
extern int amd_iommu_activate_guest_mode(void *data, int cpu);
extern int amd_iommu_deactivate_guest_mode(void *data);
#else /* defined(CONFIG_AMD_IOMMU) && defined(CONFIG_IRQ_REMAP) */
@ -48,7 +48,7 @@ static inline int amd_iommu_update_ga(int cpu, void *data)
return 0;
}
static inline int amd_iommu_activate_guest_mode(void *data)
static inline int amd_iommu_activate_guest_mode(void *data, int cpu)
{
return 0;
}