The current MSI quota handling is not race-safe and might lead
to incoherent number of MSIs allocated between the firmware and
Linux MSI data structures. I.e. if the following chain is called
from concurrently loading drivers: rtas_setup_msi_irqs() ->
msi_quota_for_device() -> traverse_pci_devices() a driver might
get a stalled value of MSI limit for its device or possibly even
crash.
This update introduces "rtas_quota_mutex" and serializes all
accesses to msi_quota_for_device() function. As result, no driver
could eat into other device's MSI limit.
Signed-off-by: Alexander Gordeev <agordeev@xxxxxxxxxx>
---
arch/powerpc/platforms/pseries/msi.c | 24 ++++++++++++++++++++++--
1 files changed, 22 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/msi.c b/arch/powerpc/platforms/pseries/msi.c
index 009ec73..0e1d288 100644
--- a/arch/powerpc/platforms/pseries/msi.c
+++ b/arch/powerpc/platforms/pseries/msi.c
@@ -26,6 +26,8 @@ static int query_token, change_token;
#define RTAS_CHANGE_MSIX_FN 4
#define RTAS_CHANGE_32MSI_FN 5
+static DEFINE_MUTEX(rtas_quota_mutex);
+
/* RTAS Helpers */
static int rtas_change_msi(struct pci_dn *pdn, u32 func, u32 num_irqs)
@@ -345,7 +347,9 @@ static int rtas_msi_check_device(struct pci_dev *pdev, int nvec, int type)
if (rc)
return rc;
+ mutex_lock(&rtas_quota_mutex);
quota = msi_quota_for_device(pdev, nvec);
+ mutex_unlock(&rtas_quota_mutex);
if (quota && quota < nvec)
return quota;
@@ -399,6 +403,7 @@ static int rtas_setup_msi_irqs(struct pci_dev *pdev, int nvec_in, int type)
struct msi_msg msg;
int nvec = nvec_in;
int use_32bit_msi_hack = 0;
+ int quota;
pdn = pci_get_pdn(pdev);
if (!pdn)
@@ -407,13 +412,21 @@ static int rtas_setup_msi_irqs(struct pci_dev *pdev, int nvec_in, int type)
if (type == PCI_CAP_ID_MSIX && check_msix_entries(pdev))
return -EINVAL;
+ mutex_lock(&rtas_quota_mutex);
+
+ quota = msi_quota_for_device(pdev, nvec);
+ if (quota && quota < nvec) {
+ mutex_unlock(&rtas_quota_mutex);
+ return quota;
+ }
+
/*
* Firmware currently refuse any non power of two allocation
* so we round up if the quota will allow it.
*/
if (type == PCI_CAP_ID_MSIX) {
int m = roundup_pow_of_two(nvec);
- int quota = msi_quota_for_device(pdev, m);
+ quota = msi_quota_for_device(pdev, m);
if (quota >= m)
nvec = m;
@@ -433,8 +446,11 @@ again:
* We only want to run the 32 bit MSI hack below if
* the max bus speed is Gen2 speed
*/
- if (pdev->bus->max_bus_speed != PCIE_SPEED_5_0GT)
+ if (pdev->bus->max_bus_speed !=
+ PCIE_SPEED_5_0GT) {
+ mutex_unlock(&rtas_quota_mutex);
return rc;
+ }
use_32bit_msi_hack = 1;
}
@@ -459,6 +475,7 @@ again:
nvec = nvec_in;
goto again;
}
+ mutex_unlock(&rtas_quota_mutex);
pr_debug("rtas_msi: rtas_change_msi() failed\n");
return rc;
}
@@ -467,6 +484,7 @@ again:
list_for_each_entry(entry, &pdev->msi_list, list) {
hwirq = rtas_query_irq_number(pdn, i++);
if (hwirq < 0) {
+ mutex_unlock(&rtas_quota_mutex);
pr_debug("rtas_msi: error (%d) getting hwirq\n", hwirq);
return hwirq;
}
@@ -474,6 +492,7 @@ again:
virq = irq_create_mapping(NULL, hwirq);
if (virq == NO_IRQ) {
+ mutex_unlock(&rtas_quota_mutex);
pr_debug("rtas_msi: Failed mapping hwirq %d\n", hwirq);
return -ENOSPC;
}
@@ -486,6 +505,7 @@ again:
entry->msg = msg;
}
+ mutex_unlock(&rtas_quota_mutex);
return 0;
}
--
1.7.7.6
--
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