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From: | Marcel Apfelbaum |
Subject: | Re: [Qemu-devel] [PATCH 1/4] hw/pcie: fix Extended Configuration Space for devices with no Extended Capabilities |
Date: | Fri, 27 Jan 2017 18:12:15 +0200 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.1 |
On 01/10/2017 05:13 AM, Michael S. Tsirkin wrote:
On Wed, Jan 04, 2017 at 09:57:15PM +0200, Marcel Apfelbaum wrote:Absence of any Extended Capabilities is required to be indicated by an Extended Capability header with a Capability ID of 0000h, a Capability Version of 0h, and a Next Capability Offset of 000h. Instead of inserting a 'NULL' capability is simpler to mark the start of the Extended Configuration Space as read-only to achieve the same behaviour. Signed-off-by: Marcel Apfelbaum <address@hidden>Kind of hacky and only theoretical - I don't think any guest writes there - but ok.
I agree is theoretical, but Windows PCI Hardware Compliance WHQL tests find it. However I think
1. we should init config to 0 too
What do you mean? Have a 'Null' capability for regular PCI capabilities list? I'll have a look on the spec to see if is required.
2. this needs a compat flag
Sure, I'll add one. Thanks, Marcel
--- hw/pci/pcie.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c index 99cfb45..62c1def 100644 --- a/hw/pci/pcie.c +++ b/hw/pci/pcie.c @@ -109,6 +109,9 @@ int pcie_cap_init(PCIDevice *dev, uint8_t offset, uint8_t type, uint8_t port) PCI_EXP_DEVCAP2_EFF | PCI_EXP_DEVCAP2_EETLPP); pci_set_word(dev->wmask + pos + PCI_EXP_DEVCTL2, PCI_EXP_DEVCTL2_EETLPPB); + + /* read-only to behave like a 'NULL' Extended Capability Header */ + pci_set_long(dev->wmask + PCI_CONFIG_SPACE_SIZE, 0); return pos; } -- 2.5.5
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