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bhyve: Appease warning about a potentially unaligned pointer.

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When initializing the device model for a PCI pass through device that
uses MSI-X, bhyve reads the MSI-X capability from the real device to
save a copy in the emulated PCI config space.  It also saves a copy in
a local struct msixcap on the stack.  Since struct msixcap is packed,
GCC complains that casting a pointer to the struct to a uint32_t
pointer may result in an unaligned pointer.

This path is not performance critical, so to appease the compiler,
simply change the pointer to a char * and use memcpy to copy the 4
bytes read in each iteration of the loop.

Reviewed by:	corvink, bz, markj
Differential Revision:	https://reviews.freebsd.org/D37490
This commit is contained in:
John Baldwin 2022-11-28 17:10:07 -08:00
parent 15cebe3d63
commit 32b21dd271
1 changed files with 4 additions and 4 deletions
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8
usr.sbin/bhyve/pci_passthru.c
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@ -212,7 +212,7 @@ cfginitmsi(struct passthru_softc *sc)
struct pcisel sel;
struct pci_devinst *pi;
struct msixcap msixcap;
uint32_t *msixcap_ptr;
char *msixcap_ptr;
pi = sc->psc_pi;
sel = sc->psc_sel;
@ -249,15 +249,15 @@ cfginitmsi(struct passthru_softc *sc)
*/
sc->psc_msix.capoff = ptr;
caplen = 12;
msixcap_ptr = (uint32_t*) &msixcap;
msixcap_ptr = (char *)&msixcap;
capptr = ptr;
while (caplen > 0) {
u32 = read_config(&sel, capptr, 4);
*msixcap_ptr = u32;
memcpy(msixcap_ptr, &u32, 4);
pci_set_cfgdata32(pi, capptr, u32);
caplen -= 4;
capptr += 4;
msixcap_ptr++;
msixcap_ptr += 4;
}
}
ptr = read_config(&sel, ptr + PCICAP_NEXTPTR, 1);