Per PCIe 5.0 r1.0, Terms and Acronyms, Page 80:
Reserved register fields must be read only and must return 0 (all 0's
for multi-bit fields) when read. Reserved encodings for register and
packet fields must not be used. Any implementation dependence on a
Reserved field value or encoding will result in an implementation that
is not PCI Express-compliant.
This patch ensures reads will return 0 for any bit not in the Read-Only,
Read-Write, or Write-1-to-Clear bitmasks.
Signed-off-by: Jon Derrick <jonathan.derrick@xxxxxxxxx>
---
drivers/pci/pci-bridge-emul.c | 30 +++++++++++++-----------------
1 file changed, 13 insertions(+), 17 deletions(-)
diff --git a/drivers/pci/pci-bridge-emul.c b/drivers/pci/pci-bridge-emul.c
index 5c0dffa601f3..aa563c8fd81e 100644
--- a/drivers/pci/pci-bridge-emul.c
+++ b/drivers/pci/pci-bridge-emul.c
@@ -24,6 +24,17 @@
#define PCI_CAP_PCIE_START PCI_BRIDGE_CONF_END
#define PCI_CAP_PCIE_END (PCI_CAP_PCIE_START + PCI_EXP_SLTSTA2 + 2)
+/**
+ * struct pci_bridge_reg_behavior - register bits behaviors
+ * @ro: Read-Only bits
+ * @rw: Read-Write bits
+ * @w1c: Write-1-to-Clear bits
+ *
+ * Reads and Writes will be filtered by specified behavior. All other bits not
+ * declared are assumed 'Reserved' and will return 0 on reads, per PCIe 5.0:
+ * "Reserved register fields must be read only and must return 0 (all 0's for
+ * multi-bit fields) when read".
+ */
struct pci_bridge_reg_behavior {
/* Read-only bits */
u32 ro;
@@ -33,9 +44,6 @@ struct pci_bridge_reg_behavior {
/* Write-1-to-clear bits */
u32 w1c;
-
- /* Reserved bits (hardwired to 0) */
- u32 rsvd;
};
static const struct pci_bridge_reg_behavior pci_regs_behavior[] = {
@@ -49,7 +57,6 @@ static const struct pci_bridge_reg_behavior pci_regs_behavior[] = {
PCI_COMMAND_FAST_BACK) |
(PCI_STATUS_CAP_LIST | PCI_STATUS_66MHZ |
PCI_STATUS_FAST_BACK | PCI_STATUS_DEVSEL_MASK) << 16),
- .rsvd = GENMASK(15, 10) | ((BIT(6) | GENMASK(3, 0)) << 16),
.w1c = PCI_STATUS_ERROR_BITS << 16,
},
[PCI_CLASS_REVISION / 4] = { .ro = ~0 },
@@ -96,8 +103,6 @@ static const struct pci_bridge_reg_behavior pci_regs_behavior[] = {
GENMASK(11, 8) | GENMASK(3, 0)),
.w1c = PCI_STATUS_ERROR_BITS << 16,
-
- .rsvd = ((BIT(6) | GENMASK(4, 0)) << 16),
},
[PCI_MEMORY_BASE / 4] = {
@@ -130,12 +135,10 @@ static const struct pci_bridge_reg_behavior pci_regs_behavior[] = {
[PCI_CAPABILITY_LIST / 4] = {
.ro = GENMASK(7, 0),
- .rsvd = GENMASK(31, 8),
},
[PCI_ROM_ADDRESS1 / 4] = {
.rw = GENMASK(31, 11) | BIT(0),
- .rsvd = GENMASK(10, 1),
},
/*
@@ -158,8 +161,6 @@ static const struct pci_bridge_reg_behavior pci_regs_behavior[] = {
.ro = (GENMASK(15, 8) | ((PCI_BRIDGE_CTL_FAST_BACK) << 16)),
.w1c = BIT(10) << 16,
-
- .rsvd = (GENMASK(15, 12) | BIT(4)) << 16,
},
};
@@ -186,13 +187,11 @@ static const struct pci_bridge_reg_behavior pcie_cap_regs_behavior[] = {
*/
.w1c = (BIT(6) | GENMASK(3, 0)) << 16,
.ro = GENMASK(5, 4) << 16,
- .rsvd = GENMASK(15, 7) << 16,
},
[PCI_EXP_LNKCAP / 4] = {
/* All bits are RO, except bit 23 which is reserved */
.ro = lower_32_bits(~BIT(23)),
- .rsvd = BIT(23),
},
[PCI_EXP_LNKCTL / 4] = {
@@ -206,7 +205,6 @@ static const struct pci_bridge_reg_behavior pcie_cap_regs_behavior[] = {
.rw = GENMASK(15, 14) | GENMASK(11, 3) | GENMASK(1, 0),
.ro = GENMASK(13, 0) << 16,
.w1c = GENMASK(15, 14) << 16,
- .rsvd = GENMASK(13, 12) | BIT(2),
},
[PCI_EXP_SLTCAP / 4] = {
@@ -224,7 +222,6 @@ static const struct pci_bridge_reg_behavior pcie_cap_regs_behavior[] = {
.rw = GENMASK(14, 0),
.w1c = (BIT(8) | GENMASK(4, 0)) << 16,
.ro = GENMASK(7, 5) << 16,
- .rsvd = BIT(15) | (GENMASK(15, 9) << 16),
},
[PCI_EXP_RTCTL / 4] = {
@@ -236,7 +233,6 @@ static const struct pci_bridge_reg_behavior pcie_cap_regs_behavior[] = {
*/
.rw = GENMASK(4, 0),
.ro = BIT(0) << 16,
- .rsvd = GENMASK(15, 5) | (GENMASK(15, 1) << 16),
},
[PCI_EXP_RTSTA / 4] = {
@@ -246,7 +242,6 @@ static const struct pci_bridge_reg_behavior pcie_cap_regs_behavior[] = {
*/
.ro = BIT(17) | GENMASK(15, 0),
.w1c = BIT(16),
- .rsvd = GENMASK(31, 18),
},
};
@@ -354,7 +349,8 @@ int pci_bridge_emul_conf_read(struct pci_bridge_emul *bridge, int where,
* Make sure we never return any reserved bit with a value
* different from 0.
*/
- *value &= ~behavior[reg / 4].rsvd;
+ *value &= behavior[reg / 4].ro | behavior[reg / 4].rw |
+ behavior[reg / 4].w1c;
if (size == 1)
*value = (*value >> (8 * (where & 3))) & 0xff;
--
2.18.1
