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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen staging] xen/pci: detect when BARs are not suitably positioned
commit 75cc460a1b8cfd8e5d2c4302234ee194defe4872
Author: Roger Pau Monné <roger.pau@xxxxxxxxxx>
AuthorDate: Thu Feb 3 13:13:19 2022 +0100
Commit: Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Feb 3 13:13:19 2022 +0100
xen/pci: detect when BARs are not suitably positioned
One of the boxes where I was attempting to boot Xen in PVH dom0 mode
has quirky firmware, as it will handover with a PCI device with memory
decoding enabled and a BAR of size 4K at address 0. Such BAR overlaps
with a RAM range on the e820.
This interacts badly with the dom0 PVH build, as BARs will be setup on
the p2m before RAM, so if there's a BAR positioned over a RAM region
it will trigger a domain crash when the dom0 builder attempts to
populate that region with a regular RAM page.
It's in general a very bad idea to have a BAR overlapping with any
memory region defined in the memory map, so add some sanity checks for
devices that are added with memory decoding enabled in order to assure
that BARs are not placed on top of memory regions defined in the
memory map. If overlaps are detected just disable the memory decoding
bit for the device and expect the hardware domain to properly position
the BAR.
Note apply_quirks must be called before check_pdev so that ignore_bars
is set when calling the later. PCI_HEADER_{NORMAL,BRIDGE}_NR_BARS
needs to be moved into pci_regs.h so it's defined even in the absence
of vPCI.
Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
xen/arch/x86/mm.c | 23 ++++++++++++++
xen/drivers/passthrough/pci.c | 71 ++++++++++++++++++++++++++++++++++++++++++-
xen/include/xen/mm.h | 2 ++
xen/include/xen/pci_regs.h | 2 ++
xen/include/xen/vpci.h | 2 --
5 files changed, 97 insertions(+), 3 deletions(-)
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 1397f83e41..98edf5b89c 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -783,6 +783,29 @@ bool is_iomem_page(mfn_t mfn)
return (page_get_owner(page) == dom_io);
}
+/* Input ranges are inclusive. */
+bool is_memory_hole(mfn_t start, mfn_t end)
+{
+ unsigned long s = mfn_x(start);
+ unsigned long e = mfn_x(end);
+ unsigned int i;
+
+ for ( i = 0; i < e820.nr_map; i++ )
+ {
+ const struct e820entry *entry = &e820.map[i];
+
+ if ( !entry->size )
+ continue;
+
+ /* Do not allow overlaps with any memory range. */
+ if ( s <= PFN_DOWN(entry->addr + entry->size - 1) &&
+ PFN_DOWN(entry->addr) <= e )
+ return false;
+ }
+
+ return true;
+}
+
static int update_xen_mappings(unsigned long mfn, unsigned int cacheattr)
{
int err = 0;
diff --git a/xen/drivers/passthrough/pci.c b/xen/drivers/passthrough/pci.c
index 1fad80362f..e8b09d77d8 100644
--- a/xen/drivers/passthrough/pci.c
+++ b/xen/drivers/passthrough/pci.c
@@ -233,6 +233,9 @@ static void check_pdev(const struct pci_dev *pdev)
PCI_STATUS_REC_TARGET_ABORT | PCI_STATUS_REC_MASTER_ABORT | \
PCI_STATUS_SIG_SYSTEM_ERROR | PCI_STATUS_DETECTED_PARITY)
u16 val;
+ unsigned int nbars = 0, rom_pos = 0, i;
+ static const char warn[] = XENLOG_WARNING
+ "%pp disabled: %sBAR [%#lx, %#lx] overlaps with memory map\n";
if ( command_mask )
{
@@ -251,6 +254,8 @@ static void check_pdev(const struct pci_dev *pdev)
switch ( pci_conf_read8(pdev->sbdf, PCI_HEADER_TYPE) & 0x7f )
{
case PCI_HEADER_TYPE_BRIDGE:
+ nbars = PCI_HEADER_BRIDGE_NR_BARS;
+ rom_pos = PCI_ROM_ADDRESS1;
if ( !bridge_ctl_mask )
break;
val = pci_conf_read16(pdev->sbdf, PCI_BRIDGE_CONTROL);
@@ -267,11 +272,75 @@ static void check_pdev(const struct pci_dev *pdev)
}
break;
+ case PCI_HEADER_TYPE_NORMAL:
+ nbars = PCI_HEADER_NORMAL_NR_BARS;
+ rom_pos = PCI_ROM_ADDRESS;
+ break;
+
case PCI_HEADER_TYPE_CARDBUS:
/* TODO */
break;
}
#undef PCI_STATUS_CHECK
+
+ /* Check if BARs overlap with other memory regions. */
+ val = pci_conf_read16(pdev->sbdf, PCI_COMMAND);
+ if ( !(val & PCI_COMMAND_MEMORY) || pdev->ignore_bars )
+ return;
+
+ pci_conf_write16(pdev->sbdf, PCI_COMMAND, val & ~PCI_COMMAND_MEMORY);
+ for ( i = 0; i < nbars; )
+ {
+ uint64_t addr, size;
+ unsigned int reg = PCI_BASE_ADDRESS_0 + i * 4;
+ int rc = 1;
+
+ if ( (pci_conf_read32(pdev->sbdf, reg) & PCI_BASE_ADDRESS_SPACE) !=
+ PCI_BASE_ADDRESS_SPACE_MEMORY )
+ goto next;
+
+ rc = pci_size_mem_bar(pdev->sbdf, reg, &addr, &size,
+ (i == nbars - 1) ? PCI_BAR_LAST : 0);
+ if ( rc < 0 )
+ /* Unable to size, better leave memory decoding disabled. */
+ return;
+ if ( size && !is_memory_hole(maddr_to_mfn(addr),
+ maddr_to_mfn(addr + size - 1)) )
+ {
+ /*
+ * Return without enabling memory decoding if BAR position is not
+ * in IO suitable memory. Let the hardware domain re-position the
+ * BAR.
+ */
+ printk(warn,
+ &pdev->sbdf, "", PFN_DOWN(addr), PFN_DOWN(addr + size - 1));
+ return;
+ }
+
+ next:
+ ASSERT(rc > 0);
+ i += rc;
+ }
+
+ if ( rom_pos &&
+ (pci_conf_read32(pdev->sbdf, rom_pos) & PCI_ROM_ADDRESS_ENABLE) )
+ {
+ uint64_t addr, size;
+ int rc = pci_size_mem_bar(pdev->sbdf, rom_pos, &addr, &size,
+ PCI_BAR_ROM);
+
+ if ( rc < 0 )
+ return;
+ if ( size && !is_memory_hole(maddr_to_mfn(addr),
+ maddr_to_mfn(addr + size - 1)) )
+ {
+ printk(warn, &pdev->sbdf, "ROM ", PFN_DOWN(addr),
+ PFN_DOWN(addr + size - 1));
+ return;
+ }
+ }
+
+ pci_conf_write16(pdev->sbdf, PCI_COMMAND, val);
}
static void apply_quirks(struct pci_dev *pdev)
@@ -399,8 +468,8 @@ static struct pci_dev *alloc_pdev(struct pci_seg *pseg, u8
bus, u8 devfn)
break;
}
- check_pdev(pdev);
apply_quirks(pdev);
+ check_pdev(pdev);
return pdev;
}
diff --git a/xen/include/xen/mm.h b/xen/include/xen/mm.h
index 5db26ed477..3be754da92 100644
--- a/xen/include/xen/mm.h
+++ b/xen/include/xen/mm.h
@@ -554,6 +554,8 @@ int __must_check steal_page(struct domain *d, struct
page_info *page,
int page_is_ram_type(unsigned long mfn, unsigned long mem_type);
/* Returns the page type(s). */
unsigned int page_get_ram_type(mfn_t mfn);
+/* Check if a range falls into a hole in the memory map. */
+bool is_memory_hole(mfn_t start, mfn_t end);
/* Prepare/destroy a ring for a dom0 helper. Helper with talk
* with Xen on behalf of this domain. */
diff --git a/xen/include/xen/pci_regs.h b/xen/include/xen/pci_regs.h
index cc4ee3b83e..ee8e82be36 100644
--- a/xen/include/xen/pci_regs.h
+++ b/xen/include/xen/pci_regs.h
@@ -88,6 +88,8 @@
* 0xffffffff to the register, and reading it back. Only
* 1 bits are decoded.
*/
+#define PCI_HEADER_NORMAL_NR_BARS 6
+#define PCI_HEADER_BRIDGE_NR_BARS 2
#define PCI_BASE_ADDRESS_0 0x10 /* 32 bits */
#define PCI_BASE_ADDRESS_1 0x14 /* 32 bits [htype 0,1 only] */
#define PCI_BASE_ADDRESS_2 0x18 /* 32 bits [htype 0 only] */
diff --git a/xen/include/xen/vpci.h b/xen/include/xen/vpci.h
index 3f32de9d7e..e8ac1eb395 100644
--- a/xen/include/xen/vpci.h
+++ b/xen/include/xen/vpci.h
@@ -80,8 +80,6 @@ struct vpci {
bool prefetchable : 1;
/* Store whether the BAR is mapped into guest p2m. */
bool enabled : 1;
-#define PCI_HEADER_NORMAL_NR_BARS 6
-#define PCI_HEADER_BRIDGE_NR_BARS 2
} bars[PCI_HEADER_NORMAL_NR_BARS + 1];
/* At most 6 BARS + 1 expansion ROM BAR. */
--
generated by git-patchbot for /home/xen/git/xen.git#staging
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