bhyve: ignore low bits of CFGADR
Bhyve could emulate wrong PCI registers. In the best case, the guest reads wrong registers and the device driver would report some errors. In the worst case, the guest writes to wrong PCI registers and could brick hardware when using PCI passthrough. According to Intels specification, low bits of CFGADR should be ignored. Some OS like linux may rely on it. Otherwise, bhyve could emulate a wrong PCI register. E.g. If linux would like to read 2 bytes from offset 0x02, following would happen. linux: outl 0x80000002 at CFGADR inw at CFGDAT + 2 bhyve: cfgoff = 0x80000002 & 0xFF = 0x02 coff = cfgoff + (port - CFGDAT) = 0x02 + 0x02 = 0x04 Bhyve would emulate the register at offset 0x04 not 0x02. Reviewed By: #bhyve, grehan Differential Revision: https://reviews.freebsd.org/D31819 Sponsored by: Beckhoff Automation GmbH & Co. KG
This commit is contained in:
parent
6495766acf
commit
1b0e2f0b60
@ -2018,7 +2018,7 @@ pci_emul_cfgaddr(struct vmctx *ctx, int vcpu, int in, int port, int bytes,
|
||||
} else {
|
||||
x = *eax;
|
||||
cfgenable = (x & CONF1_ENABLE) == CONF1_ENABLE;
|
||||
cfgoff = x & PCI_REGMAX;
|
||||
cfgoff = (x & PCI_REGMAX) & ~0x03;
|
||||
cfgfunc = (x >> 8) & PCI_FUNCMAX;
|
||||
cfgslot = (x >> 11) & PCI_SLOTMAX;
|
||||
cfgbus = (x >> 16) & PCI_BUSMAX;
|
||||
|
Loading…
Reference in New Issue
Block a user