5.15-stable review patch. If anyone has any objections, please let me know.
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From: Marek Marczykowski-Górecki marmarek@invisiblethingslab.com
[ Upstream commit 2c269f42d0f382743ab230308b836ffe5ae9b2ae ]
Linux enables MSI-X before disabling INTx, but keeps MSI-X masked until the table is filled. Then it disables INTx just before clearing MASKALL bit. Currently this approach is rejected by xen-pciback. According to the PCIe spec, device cannot use INTx when MSI/MSI-X is enabled (in other words: enabling MSI/MSI-X implicitly disables INTx).
Change the logic to consider INTx disabled if MSI/MSI-X is enabled. This applies to three places: - checking currently enabled interrupts type, - transition to MSI/MSI-X - where INTx would be implicitly disabled, - clearing INTx disable bit - which can be allowed even if MSI/MSI-X is enabled, as device should consider INTx disabled anyway in that case
Fixes: 5e29500eba2a ("xen-pciback: Allow setting PCI_MSIX_FLAGS_MASKALL too") Signed-off-by: Marek Marczykowski-Górecki marmarek@invisiblethingslab.com Acked-by: Juergen Gross jgross@suse.com Link: https://lore.kernel.org/r/20231016131348.1734721-1-marmarek@invisiblethingsl... Signed-off-by: Juergen Gross jgross@suse.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/xen/xen-pciback/conf_space.c | 19 +++++++++++------ .../xen/xen-pciback/conf_space_capability.c | 8 ++++++- drivers/xen/xen-pciback/conf_space_header.c | 21 +++---------------- 3 files changed, 23 insertions(+), 25 deletions(-)
diff --git a/drivers/xen/xen-pciback/conf_space.c b/drivers/xen/xen-pciback/conf_space.c index 059de92aea7d0..d47eee6c51435 100644 --- a/drivers/xen/xen-pciback/conf_space.c +++ b/drivers/xen/xen-pciback/conf_space.c @@ -288,12 +288,6 @@ int xen_pcibk_get_interrupt_type(struct pci_dev *dev) u16 val; int ret = 0;
- err = pci_read_config_word(dev, PCI_COMMAND, &val); - if (err) - return err; - if (!(val & PCI_COMMAND_INTX_DISABLE)) - ret |= INTERRUPT_TYPE_INTX; - /* * Do not trust dev->msi(x)_enabled here, as enabling could be done * bypassing the pci_*msi* functions, by the qemu. @@ -316,6 +310,19 @@ int xen_pcibk_get_interrupt_type(struct pci_dev *dev) if (val & PCI_MSIX_FLAGS_ENABLE) ret |= INTERRUPT_TYPE_MSIX; } + + /* + * PCIe spec says device cannot use INTx if MSI/MSI-X is enabled, + * so check for INTx only when both are disabled. + */ + if (!ret) { + err = pci_read_config_word(dev, PCI_COMMAND, &val); + if (err) + return err; + if (!(val & PCI_COMMAND_INTX_DISABLE)) + ret |= INTERRUPT_TYPE_INTX; + } + return ret ?: INTERRUPT_TYPE_NONE; }
diff --git a/drivers/xen/xen-pciback/conf_space_capability.c b/drivers/xen/xen-pciback/conf_space_capability.c index 097316a741268..1948a9700c8fa 100644 --- a/drivers/xen/xen-pciback/conf_space_capability.c +++ b/drivers/xen/xen-pciback/conf_space_capability.c @@ -236,10 +236,16 @@ static int msi_msix_flags_write(struct pci_dev *dev, int offset, u16 new_value, return PCIBIOS_SET_FAILED;
if (new_value & field_config->enable_bit) { - /* don't allow enabling together with other interrupt types */ + /* + * Don't allow enabling together with other interrupt type, but do + * allow enabling MSI(-X) while INTx is still active to please Linuxes + * MSI(-X) startup sequence. It is safe to do, as according to PCI + * spec, device with enabled MSI(-X) shouldn't use INTx. + */ int int_type = xen_pcibk_get_interrupt_type(dev);
if (int_type == INTERRUPT_TYPE_NONE || + int_type == INTERRUPT_TYPE_INTX || int_type == field_config->int_type) goto write; return PCIBIOS_SET_FAILED; diff --git a/drivers/xen/xen-pciback/conf_space_header.c b/drivers/xen/xen-pciback/conf_space_header.c index ac45cdc38e859..fcaa050d692d2 100644 --- a/drivers/xen/xen-pciback/conf_space_header.c +++ b/drivers/xen/xen-pciback/conf_space_header.c @@ -104,24 +104,9 @@ static int command_write(struct pci_dev *dev, int offset, u16 value, void *data) pci_clear_mwi(dev); }
- if (dev_data && dev_data->allow_interrupt_control) { - if ((cmd->val ^ value) & PCI_COMMAND_INTX_DISABLE) { - if (value & PCI_COMMAND_INTX_DISABLE) { - pci_intx(dev, 0); - } else { - /* Do not allow enabling INTx together with MSI or MSI-X. */ - switch (xen_pcibk_get_interrupt_type(dev)) { - case INTERRUPT_TYPE_NONE: - pci_intx(dev, 1); - break; - case INTERRUPT_TYPE_INTX: - break; - default: - return PCIBIOS_SET_FAILED; - } - } - } - } + if (dev_data && dev_data->allow_interrupt_control && + ((cmd->val ^ value) & PCI_COMMAND_INTX_DISABLE)) + pci_intx(dev, !(value & PCI_COMMAND_INTX_DISABLE));
cmd->val = value;