[RFC PATCH 23/42] iommu/vt-d: Allow pasid 0 in IOPF

Yan Zhao
2023-12-02T09:55:57Z

Pasid 0 is allowed when IOPFs are triggered in second level page tables.
Page requests/response with pasid 0 or without pasid are also permitted by
vt-d hardware spec.

FIXME:
Current .page_response and intel_svm_enable_prq() are bound to SVM and
is compiled only with CONFIG_INTEL_IOMMU_SVM.
e.g.
.page_response = intel_svm_page_response,

Need to move prq enableing and page response code outside of svm.c and
SVM independent.

Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
---
drivers/iommu/intel/svm.c | 37 ++++++++++++++++++++-----------------
1 file changed, 20 insertions(+), 17 deletions(-)

diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index 659de9c160241..a2a63a85baa9f 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -628,6 +628,7 @@ static irqreturn_t prq_event_thread(int irq, void *d)
int head, tail, handled;
struct pci_dev *pdev;
u64 address;
+ bool bad_req = false;

/*
* Clear PPR bit before reading head/tail registers, to ensure that
@@ -642,30 +643,29 @@ static irqreturn_t prq_event_thread(int irq, void *d)
req = &iommu->prq[head / sizeof(*req)];
address = (u64)req->addr << VTD_PAGE_SHIFT;

- if (unlikely(!req->pasid_present)) {
- pr_err("IOMMU: %s: Page request without PASID\n",
+ if (unlikely(!req->pasid_present))
+ pr_info("IOMMU: %s: Page request without PASID\n",
iommu->name);
-bad_req:
- handle_bad_prq_event(iommu, req, QI_RESP_INVALID);
- goto prq_advance;
- }

if (unlikely(!is_canonical_address(address))) {
pr_err("IOMMU: %s: Address is not canonical\n",
iommu->name);
- goto bad_req;
+ bad_req = true;
+ goto prq_advance;
}

if (unlikely(req->pm_req && (req->rd_req | req->wr_req))) {
pr_err("IOMMU: %s: Page request in Privilege Mode\n",
iommu->name);
- goto bad_req;
+ bad_req = true;
+ goto prq_advance;
}

if (unlikely(req->exe_req && req->rd_req)) {
pr_err("IOMMU: %s: Execution request not supported\n",
iommu->name);
- goto bad_req;
+ bad_req = true;
+ goto prq_advance;
}

/* Drop Stop Marker message. No need for a response. */
@@ -679,8 +679,10 @@ static irqreturn_t prq_event_thread(int irq, void *d)
* If prq is to be handled outside iommu driver via receiver of
* the fault notifiers, we skip the page response here.
*/
- if (!pdev)
- goto bad_req;
+ if (!pdev) {
+ bad_req = true;
+ goto prq_advance;
+ }

if (intel_svm_prq_report(iommu, &pdev->dev, req))
handle_bad_prq_event(iommu, req, QI_RESP_INVALID);
@@ -688,8 +690,14 @@ static irqreturn_t prq_event_thread(int irq, void *d)
trace_prq_report(iommu, &pdev->dev, req->qw_0, req->qw_1,
req->priv_data[0], req->priv_data[1],
iommu->prq_seq_number++);
+
pci_dev_put(pdev);
+
prq_advance:
+ if (bad_req) {
+ handle_bad_prq_event(iommu, req, QI_RESP_INVALID);
+ bad_req = false;
+ }
head = (head + sizeof(*req)) & PRQ_RING_MASK;
}

@@ -747,12 +755,7 @@ int intel_svm_page_response(struct device *dev,
private_present = prm->flags & IOMMU_FAULT_PAGE_REQUEST_PRIV_DATA;
last_page = prm->flags & IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE;

- if (!pasid_present) {
- ret = -EINVAL;
- goto out;
- }
-
- if (prm->pasid == 0 || prm->pasid >= PASID_MAX) {
+ if (prm->pasid >= PASID_MAX) {
ret = -EINVAL;
goto out;
}
--
2.17.1