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authorRusty Russell <rusty@rustcorp.com.au>2015-02-11 15:15:11 +1030
committerRusty Russell <rusty@rustcorp.com.au>2015-02-11 16:47:35 +1030
commit6a54f9ab0d65a2095de50160b8ca7ce6469aaac0 (patch)
tree20ed18c8bcc4d92b235642b94466eec1729de4fc /tools/lguest
parent0a6bcc183f5377eca07cbf0cf6f4b6cb00e4c1ec (diff)
lguest: decode mmio accesses for PCI in example launcher.
We don't do anything with them yet (emulate_mmio_write and emulate_mmio_read are stubs), but we decode the instructions and search for the device they're hitting. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'tools/lguest')
-rw-r--r--tools/lguest/lguest.c167
1 files changed, 167 insertions, 0 deletions
diff --git a/tools/lguest/lguest.c b/tools/lguest/lguest.c
index 35d7aa90aa24..e52a3571076a 100644
--- a/tools/lguest/lguest.c
+++ b/tools/lguest/lguest.c
@@ -99,6 +99,9 @@ static int lguest_fd;
/* a per-cpu variable indicating whose vcpu is currently running */
static unsigned int __thread cpu_id;
+/* 5 bit device number in the PCI_CONFIG_ADDR => 32 only */
+#define MAX_PCI_DEVICES 32
+
/* This is our list of devices. */
struct device_list {
/* Counter to assign interrupt numbers. */
@@ -114,6 +117,9 @@ struct device_list {
struct device *dev;
/* And a pointer to the last device for easy append. */
struct device *lastdev;
+
+ /* PCI devices. */
+ struct device *pci[MAX_PCI_DEVICES];
};
/* The list of Guest devices, based on command line arguments. */
@@ -140,6 +146,10 @@ struct device {
/* Is it operational */
bool running;
+ /* PCI MMIO resources (all in BAR0) */
+ size_t mmio_size;
+ u32 mmio_addr;
+
/* Device-specific data. */
void *priv;
};
@@ -1197,6 +1207,77 @@ static void setreg_off(size_t offset, u32 val)
err(1, "Setting register %u", offset);
}
+/* Get register by instruction encoding */
+static u32 getreg_num(unsigned regnum, u32 mask)
+{
+ /* 8 bit ops use regnums 4-7 for high parts of word */
+ if (mask == 0xFF && (regnum & 0x4))
+ return getreg_num(regnum & 0x3, 0xFFFF) >> 8;
+
+ switch (regnum) {
+ case 0: return getreg(eax) & mask;
+ case 1: return getreg(ecx) & mask;
+ case 2: return getreg(edx) & mask;
+ case 3: return getreg(ebx) & mask;
+ case 4: return getreg(esp) & mask;
+ case 5: return getreg(ebp) & mask;
+ case 6: return getreg(esi) & mask;
+ case 7: return getreg(edi) & mask;
+ }
+ abort();
+}
+
+/* Set register by instruction encoding */
+static void setreg_num(unsigned regnum, u32 val, u32 mask)
+{
+ /* Don't try to set bits out of range */
+ assert(~(val & ~mask));
+
+ /* 8 bit ops use regnums 4-7 for high parts of word */
+ if (mask == 0xFF && (regnum & 0x4)) {
+ /* Construct the 16 bits we want. */
+ val = (val << 8) | getreg_num(regnum & 0x3, 0xFF);
+ setreg_num(regnum & 0x3, val, 0xFFFF);
+ return;
+ }
+
+ switch (regnum) {
+ case 0: setreg(eax, val | (getreg(eax) & ~mask)); return;
+ case 1: setreg(ecx, val | (getreg(ecx) & ~mask)); return;
+ case 2: setreg(edx, val | (getreg(edx) & ~mask)); return;
+ case 3: setreg(ebx, val | (getreg(ebx) & ~mask)); return;
+ case 4: setreg(esp, val | (getreg(esp) & ~mask)); return;
+ case 5: setreg(ebp, val | (getreg(ebp) & ~mask)); return;
+ case 6: setreg(esi, val | (getreg(esi) & ~mask)); return;
+ case 7: setreg(edi, val | (getreg(edi) & ~mask)); return;
+ }
+ abort();
+}
+
+/* Get bytes of displacement appended to instruction, from r/m encoding */
+static u32 insn_displacement_len(u8 mod_reg_rm)
+{
+ /* Switch on the mod bits */
+ switch (mod_reg_rm >> 6) {
+ case 0:
+ /* If mod == 0, and r/m == 101, 16-bit displacement follows */
+ if ((mod_reg_rm & 0x7) == 0x5)
+ return 2;
+ /* Normally, mod == 0 means no literal displacement */
+ return 0;
+ case 1:
+ /* One byte displacement */
+ return 1;
+ case 2:
+ /* Four byte displacement */
+ return 4;
+ case 3:
+ /* Register mode */
+ return 0;
+ }
+ abort();
+}
+
static void emulate_insn(const u8 insn[])
{
unsigned long args[] = { LHREQ_TRAP, 13 };
@@ -1310,6 +1391,88 @@ no_emulate:
err(1, "Reinjecting trap 13 for fault at %#x", getreg(eip));
}
+static struct device *find_mmio_region(unsigned long paddr, u32 *off)
+{
+ unsigned int i;
+
+ for (i = 1; i < MAX_PCI_DEVICES; i++) {
+ struct device *d = devices.pci[i];
+
+ if (!d)
+ continue;
+ if (paddr < d->mmio_addr)
+ continue;
+ if (paddr >= d->mmio_addr + d->mmio_size)
+ continue;
+ *off = paddr - d->mmio_addr;
+ return d;
+ }
+ return NULL;
+}
+
+static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask)
+{
+}
+
+static u32 emulate_mmio_read(struct device *d, u32 off, u32 mask)
+{
+ return 0xFFFFFFFF;
+}
+
+static void emulate_mmio(unsigned long paddr, const u8 *insn)
+{
+ u32 val, off, mask = 0xFFFFFFFF, insnlen = 0;
+ struct device *d = find_mmio_region(paddr, &off);
+ unsigned long args[] = { LHREQ_TRAP, 14 };
+
+ if (!d) {
+ warnx("MMIO touching %#08lx (not a device)", paddr);
+ goto reinject;
+ }
+
+ /* Prefix makes it a 16 bit op */
+ if (insn[0] == 0x66) {
+ mask = 0xFFFF;
+ insnlen++;
+ }
+
+ /* iowrite */
+ if (insn[insnlen] == 0x89) {
+ /* Next byte is r/m byte: bits 3-5 are register. */
+ val = getreg_num((insn[insnlen+1] >> 3) & 0x7, mask);
+ emulate_mmio_write(d, off, val, mask);
+ insnlen += 2 + insn_displacement_len(insn[insnlen+1]);
+ } else if (insn[insnlen] == 0x8b) { /* ioread */
+ /* Next byte is r/m byte: bits 3-5 are register. */
+ val = emulate_mmio_read(d, off, mask);
+ setreg_num((insn[insnlen+1] >> 3) & 0x7, val, mask);
+ insnlen += 2 + insn_displacement_len(insn[insnlen+1]);
+ } else if (insn[0] == 0x88) { /* 8-bit iowrite */
+ mask = 0xff;
+ /* Next byte is r/m byte: bits 3-5 are register. */
+ val = getreg_num((insn[1] >> 3) & 0x7, mask);
+ emulate_mmio_write(d, off, val, mask);
+ insnlen = 2 + insn_displacement_len(insn[1]);
+ } else if (insn[0] == 0x8a) { /* 8-bit ioread */
+ mask = 0xff;
+ val = emulate_mmio_read(d, off, mask);
+ setreg_num((insn[1] >> 3) & 0x7, val, mask);
+ insnlen = 2 + insn_displacement_len(insn[1]);
+ } else {
+ warnx("Unknown MMIO instruction touching %#08lx:"
+ " %02x %02x %02x %02x at %u",
+ paddr, insn[0], insn[1], insn[2], insn[3], getreg(eip));
+ reinject:
+ /* Inject trap into Guest. */
+ if (write(lguest_fd, args, sizeof(args)) < 0)
+ err(1, "Reinjecting trap 14 for fault at %#x",
+ getreg(eip));
+ return;
+ }
+
+ /* Finally, we've "done" the instruction, so move past it. */
+ setreg(eip, getreg(eip) + insnlen);
+}
/*L:190
* Device Setup
@@ -2004,6 +2167,10 @@ static void __attribute__((noreturn)) run_guest(void)
verbose("Emulating instruction at %#x\n",
getreg(eip));
emulate_insn(notify.insn);
+ } else if (notify.trap == 14) {
+ verbose("Emulating MMIO at %#x\n",
+ getreg(eip));
+ emulate_mmio(notify.addr, notify.insn);
} else
errx(1, "Unknown trap %i addr %#08x\n",
notify.trap, notify.addr);

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