Specify the length of the mapping requested from 'paddr_guest2host()'.

This seems prudent to do in its own right but it also opens up the possibility
of not having to mmap the entire guest address space in the 'bhyve' process
context.

Discussed with:	grehan
Obtained from:	NetApp

usr.sbin/bhyve/acpi.c

@@ -683,13 +683,16 @@ static int
 basl_load(int fd, uint64_t off)
 {
         struct stat sb;
+	void *gaddr;
 	int err;
 
 	err = 0;
-
-	if (fstat(fd, &sb) < 0 ||
-	    read(fd, paddr_guest2host(basl_acpi_base + off), sb.st_size) < 0)
+	gaddr = paddr_guest2host(basl_acpi_base + off, sb.st_size);
+	if (gaddr != NULL) {
+		if (fstat(fd, &sb) < 0 || read(fd, gaddr, sb.st_size) < 0)
 			err = errno;
+	} else
+		err = EFAULT;
 
 	return (err);
 }

usr.sbin/bhyve/bhyverun.c

@@ -157,17 +157,19 @@ usage(int code)
 }
 
 void *
-paddr_guest2host(uintptr_t gaddr)
+paddr_guest2host(uintptr_t gaddr, size_t len)
 {
-	if (lomem_sz == 0)
-		return (NULL);
 
-	if (gaddr < lomem_sz) {
+	if (gaddr < lomem_sz && gaddr + len <= lomem_sz)
 		return ((void *)(lomem_addr + gaddr));
-	} else if (gaddr >= 4*GB && gaddr < (4*GB + himem_sz)) {
-		return ((void *)(himem_addr + gaddr - 4*GB));
-	} else
-		return (NULL);
+
+	if (gaddr >= 4*GB) {
+		gaddr -= 4*GB;
+		if (gaddr < himem_sz && gaddr + len <= himem_sz)
+			return ((void *)(himem_addr + gaddr));
+	}
+
+	return (NULL);
 }
 
 int

usr.sbin/bhyve/bhyverun.h

@@ -43,7 +43,7 @@ extern char *vmname;
 
 extern u_long lomem_sz, himem_sz;
 
-void *paddr_guest2host(uintptr_t);
+void *paddr_guest2host(uintptr_t addr, size_t len);
 
 void fbsdrun_addcpu(struct vmctx *ctx, int cpu, uint64_t rip);
 int  fbsdrun_muxed(void);

usr.sbin/bhyve/mptbl.c

@@ -41,6 +41,9 @@ __FBSDID("$FreeBSD$");
 
 #define MPTABLE_BASE		0xF0000
 
+/* floating pointer length + maximum length of configuration table */
+#define	MPTABLE_MAX_LENGTH	(65536 + 16)
+
 #define LAPIC_PADDR		0xFEE00000
 #define LAPIC_VERSION 		16
 
@@ -346,13 +349,13 @@ mptable_build(struct vmctx *ctx, int ncpu, int ioapic)
 	char 			*curraddr;
 	char 			*startaddr;
 
-	if (paddr_guest2host(0) == NULL) {
+	startaddr = paddr_guest2host(MPTABLE_BASE, MPTABLE_MAX_LENGTH);
+	if (startaddr == NULL) {
 		printf("mptable requires mapped mem\n");
 		return (ENOMEM);
 	}
 
-	startaddr = curraddr = paddr_guest2host(MPTABLE_BASE);
-
+	curraddr = startaddr;
 	mpfp = (mpfps_t)curraddr;
 	mpt_build_mpfp(mpfp, MPTABLE_BASE);
 	curraddr += sizeof(*mpfp);

usr.sbin/bhyve/pci_virtio_block.c

@@ -222,13 +222,13 @@ pci_vtblk_proc(struct pci_vtblk_softc *sc, struct vring_hqueue *hq)
 	assert(nsegs >= 3);
 	assert(nsegs < VTBLK_MAXSEGS + 2);
 
-	vid = paddr_guest2host(vd->vd_addr);
+	vid = paddr_guest2host(vd->vd_addr, vd->vd_len);
 	assert((vid->vd_flags & VRING_DESC_F_INDIRECT) == 0);
 
 	/*
 	 * The first descriptor will be the read-only fixed header
 	 */
-	vbh = paddr_guest2host(vid[0].vd_addr);
+	vbh = paddr_guest2host(vid[0].vd_addr, sizeof(struct virtio_blk_hdr));
 	assert(vid[0].vd_len == sizeof(struct virtio_blk_hdr));
 	assert(vid[0].vd_flags & VRING_DESC_F_NEXT);
 	assert((vid[0].vd_flags & VRING_DESC_F_WRITE) == 0);
@@ -247,7 +247,8 @@ pci_vtblk_proc(struct pci_vtblk_softc *sc, struct vring_hqueue *hq)
 	 * Build up the iovec based on the guest's data descriptors
 	 */
 	for (i = 1, iolen = 0; i < nsegs - 1; i++) {
-		iov[i-1].iov_base = paddr_guest2host(vid[i].vd_addr);
+		iov[i-1].iov_base = paddr_guest2host(vid[i].vd_addr,
+						     vid[i].vd_len);
 		iov[i-1].iov_len = vid[i].vd_len;
 		iolen += vid[i].vd_len;
 
@@ -265,7 +266,7 @@ pci_vtblk_proc(struct pci_vtblk_softc *sc, struct vring_hqueue *hq)
 	}
 
 	/* Lastly, get the address of the status byte */
-	status = paddr_guest2host(vid[nsegs - 1].vd_addr);
+	status = paddr_guest2host(vid[nsegs - 1].vd_addr, 1);
 	assert(vid[nsegs - 1].vd_len == 1);
 	assert((vid[nsegs - 1].vd_flags & VRING_DESC_F_NEXT) == 0);
 	assert(vid[nsegs - 1].vd_flags & VRING_DESC_F_WRITE);
@@ -341,7 +342,8 @@ pci_vtblk_ring_init(struct pci_vtblk_softc *sc, uint64_t pfn)
 	hq = &sc->vbsc_q;
 	hq->hq_size = VTBLK_RINGSZ;
 
-	hq->hq_dtable = paddr_guest2host(pfn << VRING_PFN);
+	hq->hq_dtable = paddr_guest2host(pfn << VRING_PFN,
+					 vring_size(VTBLK_RINGSZ));
 	hq->hq_avail_flags =  (uint16_t *)(hq->hq_dtable + hq->hq_size);
 	hq->hq_avail_idx = hq->hq_avail_flags + 1;
 	hq->hq_avail_ring = hq->hq_avail_flags + 2;
@@ -371,13 +373,6 @@ pci_vtblk_init(struct vmctx *ctx, struct pci_devinst *pi, char *opts)
 		return (1);
 	}
 
-	/*
-	 * Access to guest memory is required. Fail if
-	 * memory not mapped
-	 */
-	if (paddr_guest2host(0) == NULL)
-		return (1);
-
 	/*
 	 * The supplied backing file has to exist
 	 */

usr.sbin/bhyve/pci_virtio_net.c

@@ -326,7 +326,7 @@ pci_vtnet_tap_rx(struct pci_vtnet_softc *sc)
 		 * Get a pointer to the rx header, and use the
 		 * data immediately following it for the packet buffer.
 		 */
-		vrx = (struct virtio_net_rxhdr *)paddr_guest2host(vd->vd_addr);
+		vrx = paddr_guest2host(vd->vd_addr, vd->vd_len);
 		buf = (uint8_t *)(vrx + 1);
 
 		len = read(sc->vsc_tapfd, buf,
@@ -434,7 +434,7 @@ pci_vtnet_proctx(struct pci_vtnet_softc *sc, struct vring_hqueue *hq)
 	for (i = 0, plen = 0;
 	     i < VTNET_MAXSEGS;
 	     i++, vd = &hq->hq_dtable[vd->vd_next]) {
-		iov[i].iov_base = paddr_guest2host(vd->vd_addr);
+		iov[i].iov_base = paddr_guest2host(vd->vd_addr, vd->vd_len);
 		iov[i].iov_len = vd->vd_len;
 		plen += vd->vd_len;
 		tlen += vd->vd_len;
@@ -517,7 +517,8 @@ pci_vtnet_ring_init(struct pci_vtnet_softc *sc, uint64_t pfn)
 	hq = &sc->vsc_hq[qnum];
 	hq->hq_size = pci_vtnet_qsize(qnum);
 
-	hq->hq_dtable = paddr_guest2host(pfn << VRING_PFN);
+	hq->hq_dtable = paddr_guest2host(pfn << VRING_PFN,
+					 vring_size(hq->hq_size));
 	hq->hq_avail_flags =  (uint16_t *)(hq->hq_dtable + hq->hq_size);
 	hq->hq_avail_idx = hq->hq_avail_flags + 1;
 	hq->hq_avail_ring = hq->hq_avail_flags + 2;
@@ -541,13 +542,6 @@ pci_vtnet_init(struct vmctx *ctx, struct pci_devinst *pi, char *opts)
 	struct pci_vtnet_softc *sc;
 	const char *env_msi;
 
-	/*
-	 * Access to guest memory is required. Fail if
-	 * memory not mapped
-	 */
-	if (paddr_guest2host(0) == NULL)
-		return (1);
-
 	sc = malloc(sizeof(struct pci_vtnet_softc));
 	memset(sc, 0, sizeof(struct pci_vtnet_softc));
 

usr.sbin/bhyve/virtio.h

@@ -85,4 +85,19 @@ struct virtio_used {
 #define VTCFG_R_CFG1		24	/* With MSI-X */
 #define VTCFG_R_MSIX		20
 
+/* From section 2.3, "Virtqueue Configuration", of the virtio specification */
+static inline u_int
+vring_size(u_int qsz)
+{
+	u_int size;
+
+	size = sizeof(struct virtio_desc) * qsz + sizeof(uint16_t) * (3 + qsz);
+	size = roundup2(size, VRING_ALIGN);
+
+	size += sizeof(uint16_t) * 3 + sizeof(struct virtio_used) * qsz;
+	size = roundup2(size, VRING_ALIGN);
+
+	return (size);
+}
+
 #endif	/* _VIRTIO_H_ */