On 26.10.21 10:50, Roger Pau Monné wrote:
> On Thu, Sep 30, 2021 at 10:52:17AM +0300, Oleksandr Andrushchenko wrote:
>> From: Oleksandr Andrushchenko <oleksandr_andrushche...@epam.com>
>>
>> Emulate guest BAR register values: this allows creating a guest view
>> of the registers and emulates size and properties probe as it is done
>> during PCI device enumeration by the guest.
>>
>> ROM BAR is only handled for the hardware domain and for guest domains
>> there is a stub: at the moment PCI expansion ROM is x86 only, so it
>> might not be used by other architectures without emulating x86. Other
>> use-cases may include using that expansion ROM before Xen boots, hence
>> no emulation is needed in Xen itself. Or when a guest wants to use the
>> ROM code which seems to be rare.
>>
>> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushche...@epam.com>
>> Reviewed-by: Michal Orzel <michal.or...@arm.com>
>> ---
>> Since v1:
>> - re-work guest read/write to be much simpler and do more work on write
>> than read which is expected to be called more frequently
>> - removed one too obvious comment
>>
>> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushche...@epam.com>
>> ---
>> xen/drivers/vpci/header.c | 30 +++++++++++++++++++++++++++++-
>> xen/include/xen/vpci.h | 3 +++
>> 2 files changed, 32 insertions(+), 1 deletion(-)
>>
>> diff --git a/xen/drivers/vpci/header.c b/xen/drivers/vpci/header.c
>> index 1ce98795fcca..ec4d215f36ff 100644
>> --- a/xen/drivers/vpci/header.c
>> +++ b/xen/drivers/vpci/header.c
>> @@ -400,12 +400,38 @@ static void bar_write(const struct pci_dev *pdev,
>> unsigned int reg,
>> static void guest_bar_write(const struct pci_dev *pdev, unsigned int reg,
>> uint32_t val, void *data)
>> {
>> + struct vpci_bar *bar = data;
>> + bool hi = false;
>> +
>> + if ( bar->type == VPCI_BAR_MEM64_HI )
>> + {
>> + ASSERT(reg > PCI_BASE_ADDRESS_0);
>> + bar--;
>> + hi = true;
>> + }
>> + else
>> + {
>> + val &= PCI_BASE_ADDRESS_MEM_MASK;
>> + val |= bar->type == VPCI_BAR_MEM32 ? PCI_BASE_ADDRESS_MEM_TYPE_32
>> + : PCI_BASE_ADDRESS_MEM_TYPE_64;
>> + val |= bar->prefetchable ? PCI_BASE_ADDRESS_MEM_PREFETCH : 0;
>> + }
>> +
>> + bar->guest_addr &= ~(0xffffffffull << (hi ? 32 : 0));
>> + bar->guest_addr |= (uint64_t)val << (hi ? 32 : 0);
>> +
>> + bar->guest_addr &= ~(bar->size - 1) | ~PCI_BASE_ADDRESS_MEM_MASK;
>> }
>>
>> static uint32_t guest_bar_read(const struct pci_dev *pdev, unsigned int
>> reg,
>> void *data)
>> {
>> - return 0xffffffff;
>> + const struct vpci_bar *bar = data;
>> +
>> + if ( bar->type == VPCI_BAR_MEM64_HI )
>> + return bar->guest_addr >> 32;
>> +
>> + return bar->guest_addr;
> I think this is missing a check for whether the BAR is the high part
> of a 64bit one? Ie:
>
> struct vpci_bar *bar = data;
> bool hi = false;
>
> if ( bar->type == VPCI_BAR_MEM64_HI )
> {
> ASSERT(reg > PCI_BASE_ADDRESS_0);
> bar--;
> hi = true;
> }
>
> return bar->guest_addr >> (hi ? 32 : 0);
>
> Or else when accessing the high part of a 64bit BAR you will always
> return 0s as it hasn't been setup by guest_bar_write.
Yes, you are right
> Thanks, Roger.
Thank you,
Oleksandr
