Re: [PATCH 07/10] iommu/vt-d: Replace Intel specific PASID allocator with IOASID

From: Lu Baolu
Date: Sun Nov 17 2019 - 20:46:06 EST


Hi,

On 11/16/19 7:09 AM, Jacob Pan wrote:
Make use of generic IOASID code to manage PASID allocation,
free, and lookup. Replace Intel specific code.
IOASID allocator is inclusive for both start and end of the allocation
range. The current code is based on IDR, which is exclusive for
the end of the allocation range. This patch fixes the off-by-one
error in intel_svm_bind_mm, where pasid_max - 1 is used for the end of
allocation range.

Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
Reviewed-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>

Two nit comments in line. With that fixed,

Acked-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>

Best regards,
baolu

---
drivers/iommu/Kconfig | 1 +
drivers/iommu/intel-iommu.c | 12 ++++++------
drivers/iommu/intel-pasid.c | 36 ------------------------------------
drivers/iommu/intel-svm.c | 41 +++++++++++++++++++++++++++--------------
4 files changed, 34 insertions(+), 56 deletions(-)

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index fd50ddffffbf..43ce450a40d3 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -212,6 +212,7 @@ config INTEL_IOMMU_SVM
depends on INTEL_IOMMU && X86
select PCI_PASID
select MMU_NOTIFIER
+ select IOASID
help
Shared Virtual Memory (SVM) provides a facility for devices
to access DMA resources through process address space by
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index d598168e410d..844dcf8cbc61 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -5238,7 +5238,7 @@ static void auxiliary_unlink_device(struct dmar_domain *domain,
domain->auxd_refcnt--;
if (!domain->auxd_refcnt && domain->default_pasid > 0)
- intel_pasid_free_id(domain->default_pasid);
+ ioasid_free(domain->default_pasid);
}
static int aux_domain_add_dev(struct dmar_domain *domain,
@@ -5256,10 +5256,10 @@ static int aux_domain_add_dev(struct dmar_domain *domain,
if (domain->default_pasid <= 0) {
int pasid;
- pasid = intel_pasid_alloc_id(domain, PASID_MIN,
- pci_max_pasids(to_pci_dev(dev)),
- GFP_KERNEL);
- if (pasid <= 0) {
+ /* No private data needed for the default pasid */
+ pasid = ioasid_alloc(NULL, PASID_MIN, pci_max_pasids(to_pci_dev(dev)) - 1,
+ NULL);

Nit - short line within 80 characters and align the new line with
open parenthesis.

+ if (pasid == INVALID_IOASID) {
pr_err("Can't allocate default pasid\n");
return -ENODEV;
}
@@ -5295,7 +5295,7 @@ static int aux_domain_add_dev(struct dmar_domain *domain,
spin_unlock(&iommu->lock);
spin_unlock_irqrestore(&device_domain_lock, flags);
if (!domain->auxd_refcnt && domain->default_pasid > 0)
- intel_pasid_free_id(domain->default_pasid);
+ ioasid_free(domain->default_pasid);
return ret;
}
diff --git a/drivers/iommu/intel-pasid.c b/drivers/iommu/intel-pasid.c
index 732bfee228df..3cb569e76642 100644
--- a/drivers/iommu/intel-pasid.c
+++ b/drivers/iommu/intel-pasid.c
@@ -26,42 +26,6 @@
*/
static DEFINE_SPINLOCK(pasid_lock);
u32 intel_pasid_max_id = PASID_MAX;
-static DEFINE_IDR(pasid_idr);
-
-int intel_pasid_alloc_id(void *ptr, int start, int end, gfp_t gfp)
-{
- int ret, min, max;
-
- min = max_t(int, start, PASID_MIN);
- max = min_t(int, end, intel_pasid_max_id);
-
- WARN_ON(in_interrupt());
- idr_preload(gfp);
- spin_lock(&pasid_lock);
- ret = idr_alloc(&pasid_idr, ptr, min, max, GFP_ATOMIC);
- spin_unlock(&pasid_lock);
- idr_preload_end();
-
- return ret;
-}
-
-void intel_pasid_free_id(int pasid)
-{
- spin_lock(&pasid_lock);
- idr_remove(&pasid_idr, pasid);
- spin_unlock(&pasid_lock);
-}
-
-void *intel_pasid_lookup_id(int pasid)
-{
- void *p;
-
- spin_lock(&pasid_lock);
- p = idr_find(&pasid_idr, pasid);
- spin_unlock(&pasid_lock);
-
- return p;
-}
/*
* Per device pasid table management:
diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
index b5537f27592f..a223ae93b269 100644
--- a/drivers/iommu/intel-svm.c
+++ b/drivers/iommu/intel-svm.c
@@ -17,6 +17,7 @@
#include <linux/dmar.h>
#include <linux/interrupt.h>
#include <linux/mm_types.h>
+#include <linux/ioasid.h>
#include <asm/page.h>
#include "intel-pasid.h"
@@ -335,16 +336,15 @@ int intel_svm_bind_mm(struct device *dev, int *pasid, int flags, struct svm_dev_
if (pasid_max > intel_pasid_max_id)
pasid_max = intel_pasid_max_id;
- /* Do not use PASID 0 in caching mode (virtualised IOMMU) */
- ret = intel_pasid_alloc_id(svm,
- !!cap_caching_mode(iommu->cap),
- pasid_max, GFP_KERNEL);
- if (ret < 0) {
+ /* Do not use PASID 0, reserved for RID to PASID */
+ svm->pasid = ioasid_alloc(NULL, PASID_MIN,
+ pasid_max - 1, svm);

Nit - open parenthesis alignment.

+ if (svm->pasid == INVALID_IOASID) {
kfree(svm);
kfree(sdev);
+ ret = -ENOSPC;
goto out;
}
- svm->pasid = ret;
svm->notifier.ops = &intel_mmuops;
svm->mm = mm;
svm->flags = flags;
@@ -354,7 +354,7 @@ int intel_svm_bind_mm(struct device *dev, int *pasid, int flags, struct svm_dev_
if (mm) {
ret = mmu_notifier_register(&svm->notifier, mm);
if (ret) {
- intel_pasid_free_id(svm->pasid);
+ ioasid_free(svm->pasid);
kfree(svm);
kfree(sdev);
goto out;
@@ -370,7 +370,7 @@ int intel_svm_bind_mm(struct device *dev, int *pasid, int flags, struct svm_dev_
if (ret) {
if (mm)
mmu_notifier_unregister(&svm->notifier, mm);
- intel_pasid_free_id(svm->pasid);
+ ioasid_free(svm->pasid);
kfree(svm);
kfree(sdev);
goto out;
@@ -418,7 +418,15 @@ int intel_svm_unbind_mm(struct device *dev, int pasid)
if (!iommu)
goto out;
- svm = intel_pasid_lookup_id(pasid);
+ svm = ioasid_find(NULL, pasid, NULL);
+ if (!svm)
+ goto out;
+
+ if (IS_ERR(svm)) {
+ ret = PTR_ERR(svm);
+ goto out;
+ }
+
if (!svm)
goto out;
@@ -440,7 +448,9 @@ int intel_svm_unbind_mm(struct device *dev, int pasid)
kfree_rcu(sdev, rcu);
if (list_empty(&svm->devs)) {
- intel_pasid_free_id(svm->pasid);
+ /* Clear private data so that free pass check */
+ ioasid_set_data(svm->pasid, NULL);
+ ioasid_free(svm->pasid);
if (svm->mm)
mmu_notifier_unregister(&svm->notifier, svm->mm);
@@ -475,10 +485,14 @@ int intel_svm_is_pasid_valid(struct device *dev, int pasid)
if (!iommu)
goto out;
- svm = intel_pasid_lookup_id(pasid);
+ svm = ioasid_find(NULL, pasid, NULL);
if (!svm)
goto out;
+ if (IS_ERR(svm)) {
+ ret = PTR_ERR(svm);
+ goto out;
+ }
/* init_mm is used in this case */
if (!svm->mm)
ret = 1;
@@ -585,13 +599,12 @@ static irqreturn_t prq_event_thread(int irq, void *d)
if (!svm || svm->pasid != req->pasid) {
rcu_read_lock();
- svm = intel_pasid_lookup_id(req->pasid);
+ svm = ioasid_find(NULL, req->pasid, NULL);
/* It *can't* go away, because the driver is not permitted
* to unbind the mm while any page faults are outstanding.
* So we only need RCU to protect the internal idr code. */
rcu_read_unlock();
-
- if (!svm) {
+ if (IS_ERR_OR_NULL(svm)) {
pr_err("%s: Page request for invalid PASID %d: %08llx %08llx\n",
iommu->name, req->pasid, ((unsigned long long *)req)[0],
((unsigned long long *)req)[1]);