git: 273fef1f9b0f - stable/13 - Only use byte register access in legacy virtio pci

[Andrew Turner]

The branch stable/13 has been updated by andrew:

URL: https://cgit.FreeBSD.org/src/commit/?id=273fef1f9b0f60ef37f85a6067299a07bca2ec82

commit 273fef1f9b0f60ef37f85a6067299a07bca2ec82
Author:     Andrew Turner <andrew at FreeBSD.org>
AuthorDate: 2021-08-05 14:36:07 +0000
Commit:     Andrew Turner <andrew at FreeBSD.org>
CommitDate: 2021-09-27 08:36:38 +0000

    Only use byte register access in legacy virtio pci
    
    Some simulators don't implement arbitrary sized memory access to the
    virtio PCI registers. Follow Linux and use single byte accesses to read
    and write to these registers.
    
    Reviewed by:    bryanv, emaste (previous version)
    Sponsored by:   The FreeBSD Foundation
    Differential Revision:  https://reviews.freebsd.org/D31424
    
    (cherry picked from commit 89c085b8993d7d1e7b137f99fa6df94c37c3a68a)
---
 sys/dev/virtio/pci/virtio_pci_legacy.c | 32 ++++++++------------------------
 1 file changed, 8 insertions(+), 24 deletions(-)

diff --git a/sys/dev/virtio/pci/virtio_pci_legacy.c b/sys/dev/virtio/pci/virtio_pci_legacy.c
index a17dd22aa953..2cebee720975 100644
--- a/sys/dev/virtio/pci/virtio_pci_legacy.c
+++ b/sys/dev/virtio/pci/virtio_pci_legacy.c
@@ -506,22 +506,14 @@ vtpci_legacy_read_dev_config(device_t dev, bus_size_t offset,
 	struct vtpci_legacy_softc *sc;
 	bus_size_t off;
 	uint8_t *d;
-	int size;
+	int i;
 
 	sc = device_get_softc(dev);
 	off = VIRTIO_PCI_LEGACY_CONFIG(sc) + offset;
 
-	for (d = dst; length > 0; d += size, off += size, length -= size) {
-		if (length >= 4) {
-			size = 4;
-			*(uint32_t *)d = vtpci_legacy_read_config_4(sc, off);
-		} else if (length >= 2) {
-			size = 2;
-			*(uint16_t *)d = vtpci_legacy_read_config_2(sc, off);
-		} else {
-			size = 1;
-			*d = vtpci_legacy_read_config_1(sc, off);
-		}
+	d = dst;
+	for (i = 0; i < length; i++) {
+		d[i] = vtpci_legacy_read_config_1(sc, off + i);
 	}
 }
 
@@ -532,22 +524,14 @@ vtpci_legacy_write_dev_config(device_t dev, bus_size_t offset,
 	struct vtpci_legacy_softc *sc;
 	bus_size_t off;
 	uint8_t *s;
-	int size;
+	int i;
 
 	sc = device_get_softc(dev);
 	off = VIRTIO_PCI_LEGACY_CONFIG(sc) + offset;
 
-	for (s = src; length > 0; s += size, off += size, length -= size) {
-		if (length >= 4) {
-			size = 4;
-			vtpci_legacy_write_config_4(sc, off, *(uint32_t *)s);
-		} else if (length >= 2) {
-			size = 2;
-			vtpci_legacy_write_config_2(sc, off, *(uint16_t *)s);
-		} else {
-			size = 1;
-			vtpci_legacy_write_config_1(sc, off, *s);
-		}
+	s = src;
+	for (i = 0; i < length; i++) {
+		vtpci_legacy_write_config_1(sc, off + i, s[i]);
 	}
 }