[PATCH] pci: fix setup of 64-bit BARs

[Mark Cave-Ayland]

The current PCI implementation is designed for a 32-bit PCI bus. When
a 64-bit BAR is encountered during PCI bus enumeration, currently we
treat the MSB BAR the same as a standard 32-bit BAR, attempting to guess
its size by setting to 0xffffffff and reading back the response which
returns back an invalid size of 0 and fails.

This has the effect of setting the MSB BAR to 0xffffffff meaning that
64-bit BARs are mapped at the top of PCI memory in the wrong location.

Handle this case by ignoring the MSB BAR when we detect a 64-bit BAR
leaving it at its default value of zero. This solves the issue by
ensuring that all 64-bit BARs are mapped within 32-bit PCI space which
is fine for the PPC/SPARC64 machines we care about.

Most noticeably this solves the issue of virtio modern devices (which
use 64-bit BARs under QEMU) causing a kernel panic upon startup on
qemu-system-sparc64 because they are mapped at the wrong address by OpenBIOS.

Signed-off-by: Mark Cave-Ayland 
---
 drivers/pci.c |   12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/pci.c b/drivers/pci.c
index c998280..2e09d0a 100644
--- a/drivers/pci.c
+++ b/drivers/pci.c
@@ -1202,9 +1202,9 @@ ob_pci_configure(pci_addr addr, pci_config_t *config, int num_regs, int rom_bar,
                  unsigned long *mem_base, unsigned long *io_base)

{
-        uint32_t omask;
+        uint32_t omask, mask;
         uint16_t cmd;
-        int reg;
+        int reg, flags, space_code;
         pci_addr config_addr;

ob_pci_configure_irq(addr, config);
@@ -1216,6 +1216,14 @@ ob_pci_configure(pci_addr addr, pci_config_t *config, int num_regs, int rom_bar,
                 ob_pci_configure_bar(addr, config, reg, config_addr,
                                      &omask, mem_base,
                                      io_base);
+
+                /* Ignore 64-bit BAR MSBs (always map in 32-bit space) */
+                pci_decode_pci_addr(config->assigned[reg],
+                                    &flags, &space_code, &mask);
+
+                if (space_code == MEMORY_SPACE_64) {
+                    reg++;
+                }
         }

if (rom_bar) {

[Mark Cave-Ayland]

On 11/03/17 14:38, Mark Cave-Ayland wrote:
> The current PCI implementation is designed for a 32-bit PCI bus. When
> a 64-bit BAR is encountered during PCI bus enumeration, currently we
> treat the MSB BAR the same as a standard 32-bit BAR, attempting to guess
> its size by setting to 0xffffffff and reading back the response which
> returns back an invalid size of 0 and fails.
>
> This has the effect of setting the MSB BAR to 0xffffffff meaning that
> 64-bit BARs are mapped at the top of PCI memory in the wrong location.
>
> Handle this case by ignoring the MSB BAR when we detect a 64-bit BAR
> leaving it at its default value of zero. This solves the issue by
> ensuring that all 64-bit BARs are mapped within 32-bit PCI space which
> is fine for the PPC/SPARC64 machines we care about.
>
> Most noticeably this solves the issue of virtio modern devices (which
> use 64-bit BARs under QEMU) causing a kernel panic upon startup on
> qemu-system-sparc64 because they are mapped at the wrong address by OpenBIOS.
> Signed-off-by: Mark Cave-Ayland
>
> drivers/pci.c |   12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci.c b/drivers/pci.c
> index c998280..2e09d0a 100644
> --- a/drivers/pci.c
> +++ b/drivers/pci.c
> @@ -1202,9 +1202,9 @@ ob_pci_configure(pci_addr addr, pci_config_t *config, int num_regs, int rom_bar,
>                   unsigned long *mem_base, unsigned long *io_base)
>
> {
>    uint32_t omask;
>    uint32_t omask, mask;
>    uint16_t cmd;
>    int reg;
>    int reg, flags, space_code;
>    pci_addr config_addr;
>
>    ob_pci_configure_irq(addr, config);
>
> @@ -1216,6 +1216,14 @@ ob_pci_configure(pci_addr addr, pci_config_t *config, int num_regs, int rom_bar,
>                  ob_pci_configure_bar(addr, config, reg, config_addr,
>                                       &omask, mem_base,
>                                       io_base);
>            /* Ignore 64-bit BAR MSBs (always map in 32-bit space) */
>            pci_decode_pci_addr(config->assigned[reg],
>                                &flags, &space_code, &mask);
>            if (space_code == MEMORY_SPACE_64) {
>                reg++;
>            }
>    }
>
>    if (rom_bar) {

No further comments, so pushed to git master.

ATB,

Mark.