[25/67] iommu/amd: KVM: SVM: Use pi_desc_addr to derive ga_root_ptr

Commit Message

Sean Christopherson April 4, 2025, 7:38 p.m. UTC

Use vcpu_data.pi_desc_addr instead of amd_iommu_pi_data.base to get the
GA root pointer.  KVM is the only source of amd_iommu_pi_data.base, and
KVM's one and only path for writing amd_iommu_pi_data.base computes the
exact same value for vcpu_data.pi_desc_addr and amd_iommu_pi_data.base,
and fills amd_iommu_pi_data.base if and only if vcpu_data.pi_desc_addr is
valid, i.e. amd_iommu_pi_data.base is fully redundant.

Cc: Maxim Levitsky <[e-mail]>
Reviewed-by: Joao Martins <[e-mail]>
Signed-off-by: Sean Christopherson <[e-mail]>
---
 arch/x86/kvm/svm/avic.c   | 7 +++++--
 drivers/iommu/amd/iommu.c | 2 +-
 include/linux/amd-iommu.h | 1 -
 3 files changed, 6 insertions(+), 4 deletions(-)

Patch

diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 60e6e82fe41f..9024b9fbca53 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -902,8 +902,11 @@  int avic_pi_update_irte(struct kvm_kernel_irqfd *irqfd, struct kvm *kvm,
 
 			enable_remapped_mode = false;
 
-			/* Try to enable guest_mode in IRTE */
-			pi.base = avic_get_backing_page_address(svm);
+			/*
+			 * Try to enable guest_mode in IRTE.  Note, the address
+			 * of the vCPU's AVIC backing page is passed to the
+			 * IOMMU via vcpu_info->pi_desc_addr.
+			 */
 			pi.ga_tag = AVIC_GATAG(to_kvm_svm(kvm)->avic_vm_id,
 						     svm->vcpu.vcpu_id);
 			pi.is_guest_mode = true;
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 4f69a37cf143..635774642b89 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -3860,7 +3860,7 @@  static int amd_ir_set_vcpu_affinity(struct irq_data *data, void *vcpu_info)
 
 	pi_data->prev_ga_tag = ir_data->cached_ga_tag;
 	if (pi_data->is_guest_mode) {
-		ir_data->ga_root_ptr = (pi_data->base >> 12);
+		ir_data->ga_root_ptr = (vcpu_pi_info->pi_desc_addr >> 12);
 		ir_data->ga_vector = vcpu_pi_info->vector;
 		ir_data->ga_tag = pi_data->ga_tag;
 		ret = amd_iommu_activate_guest_mode(ir_data);
diff --git a/include/linux/amd-iommu.h b/include/linux/amd-iommu.h
index 062fbd4c9b77..4f433ef39188 100644
--- a/include/linux/amd-iommu.h
+++ b/include/linux/amd-iommu.h
@@ -20,7 +20,6 @@  struct amd_iommu;
 struct amd_iommu_pi_data {
 	u32 ga_tag;
 	u32 prev_ga_tag;
-	u64 base;
 	bool is_guest_mode;
 	struct vcpu_data *vcpu_data;
 	void *ir_data;