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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 1/1] vl.c: Add pci_hole_min_size machine option.
On Tue, Mar 04, 2014 at 11:36:44AM -0500, Don Slutz wrote:
> On 03/04/14 02:34, Michael S. Tsirkin wrote:
> >On Thu, Feb 27, 2014 at 05:32:23PM -0500, Don Slutz wrote:
> >>This allows growing the pci_hole to the size needed.
> >>
> >>Signed-off-by: Don Slutz <dslutz@xxxxxxxxxxx>
> >Could you supply the motivation for this change please?
> >
>
> If you add enough PCI devices then all mmio may not fit below 4G which may
> not be the layout the user wanted. This allows you to increase the below 4G
> address space that PCI devices can use and therefore in more cases not have
> any mmio that is above 4G.
>
> There are real PCI cards that do not support mmio over 4G, so if you want to
> emulate them precisely, you may also need to increase the space below 4G for
> them. There are drivers for these cards that also do not work if they have
> their mmio space mapped above 4G.
>
> -Don Slutz
>
OK limiting low RAM size might work for this, but we need to notify
BIOS about low RAM size, and teahc BIOS to use it, right?
>
> >>---
> >> hw/i386/pc_piix.c | 14 ++++++++++++--
> >> hw/i386/pc_q35.c | 14 ++++++++++++--
> >> include/hw/i386/pc.h | 3 +++
> >> vl.c | 16 ++++++++++++++++
> >> xen-all.c | 28 +++++++++++++++++-----------
> >> 5 files changed, 60 insertions(+), 15 deletions(-)
> >>
> >>diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> >>index d5dc1ef..58e273d 100644
> >>--- a/hw/i386/pc_piix.c
> >>+++ b/hw/i386/pc_piix.c
> >>@@ -95,6 +95,7 @@ static void pc_init1(QEMUMachineInitArgs *args,
> >> DeviceState *icc_bridge;
> >> FWCfgState *fw_cfg = NULL;
> >> PcGuestInfo *guest_info;
> >>+ ram_addr_t lowmem = 0xe0000000;
> >> if (xen_enabled() && xen_hvm_init(&ram_memory) != 0) {
> >> fprintf(stderr, "xen hardware virtual machine initialisation
> >> failed\n");
> >>@@ -111,6 +112,11 @@ static void pc_init1(QEMUMachineInitArgs *args,
> >> kvmclock_create();
> >> }
> >>+ /* Adjust for pci_hole_min_size */
> >>+ if (pci_hole_min_size > ((1ULL << 32) - lowmem)) {
> >>+ lowmem = (1ULL << 32) - pci_hole_min_size;
> >>+ }
> >>+
> >> /* Check whether RAM fits below 4G (leaving 1/2 GByte for IO memory).
> >> * If it doesn't, we need to split it in chunks below and above 4G.
> >> * In any case, try to make sure that guest addresses aligned at
> >>@@ -118,8 +124,12 @@ static void pc_init1(QEMUMachineInitArgs *args,
> >> * For old machine types, use whatever split we used historically to
> >> avoid
> >> * breaking migration.
> >> */
> >>- if (args->ram_size >= 0xe0000000) {
> >>- ram_addr_t lowmem = gigabyte_align ? 0xc0000000 : 0xe0000000;
> >>+ if (args->ram_size >= lowmem) {
> >>+ lowmem = gigabyte_align ? 0xc0000000 : 0xe0000000;
> >>+ /* Adjust for pci_hole_min_size */
> >>+ if (pci_hole_min_size > ((1ULL << 32) - lowmem)) {
> >>+ lowmem = (1ULL << 32) - pci_hole_min_size;
> >>+ }
> >> above_4g_mem_size = args->ram_size - lowmem;
> >> below_4g_mem_size = lowmem;
> >> } else {
> >
> >In fact, on piix there's no pci hole as such.
> >Instead, whatever is not claimed by any other device, is PCI.
> >So the name seems awkward for this case.
> >Same applies to q35, but I didn't check xen.
> >
> >>diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> >>index a7f6260..a491f6a 100644
> >>--- a/hw/i386/pc_q35.c
> >>+++ b/hw/i386/pc_q35.c
> >>@@ -82,6 +82,7 @@ static void pc_q35_init(QEMUMachineInitArgs *args)
> >> PCIDevice *ahci;
> >> DeviceState *icc_bridge;
> >> PcGuestInfo *guest_info;
> >>+ ram_addr_t lowmem = 0xb0000000;
> >> if (xen_enabled() && xen_hvm_init(&ram_memory) != 0) {
> >> fprintf(stderr, "xen hardware virtual machine initialisation
> >> failed\n");
> >>@@ -97,6 +98,11 @@ static void pc_q35_init(QEMUMachineInitArgs *args)
> >> kvmclock_create();
> >>+ /* Adjust for pci_hole_min_size */
> >>+ if (pci_hole_min_size > ((1ULL << 32) - lowmem)) {
> >>+ lowmem = (1ULL << 32) - pci_hole_min_size;
> >>+ }
> >>+
> >> /* Check whether RAM fits below 4G (leaving 1/2 GByte for IO memory
> >> * and 256 Mbytes for PCI Express Enhanced Configuration Access
> >> Mapping
> >> * also known as MMCFG).
> >>@@ -106,8 +112,12 @@ static void pc_q35_init(QEMUMachineInitArgs *args)
> >> * For old machine types, use whatever split we used historically to
> >> avoid
> >> * breaking migration.
> >> */
> >>- if (args->ram_size >= 0xb0000000) {
> >>- ram_addr_t lowmem = gigabyte_align ? 0x80000000 : 0xb0000000;
> >>+ if (args->ram_size >= lowmem) {
> >>+ lowmem = gigabyte_align ? 0x80000000 : 0xb0000000;
> >>+ /* Adjust for pci_hole_min_size */
> >>+ if (pci_hole_min_size > ((1ULL << 32) - lowmem)) {
> >>+ lowmem = (1ULL << 32) - pci_hole_min_size;
> >>+ }
> >> above_4g_mem_size = args->ram_size - lowmem;
> >> below_4g_mem_size = lowmem;
> >> } else {
> >>diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> >>index 9010246..43ea04b 100644
> >>--- a/include/hw/i386/pc.h
> >>+++ b/include/hw/i386/pc.h
> >>@@ -204,6 +204,9 @@ int isa_vga_mm_init(hwaddr vram_base,
> >> hwaddr ctrl_base, int it_shift,
> >> MemoryRegion *address_space);
> >>+/* vl.c */
> >>+extern uint64_t pci_hole_min_size;
> >>+
> >> /* ne2000.c */
> >> static inline bool isa_ne2000_init(ISABus *bus, int base, int irq,
> >> NICInfo *nd)
> >> {
> >>diff --git a/vl.c b/vl.c
> >>index 1d27b34..32266d3 100644
> >>--- a/vl.c
> >>+++ b/vl.c
> >>@@ -123,6 +123,7 @@ int main(int argc, char **argv)
> >> #include "qom/object_interfaces.h"
> >> #define DEFAULT_RAM_SIZE 128
> >>+#define MAX_PCI_HOLE_SIZE ((1ULL << 32) - 16 * 1024 * 1024)
> >> #define MAX_VIRTIO_CONSOLES 1
> >> #define MAX_SCLP_CONSOLES 1
> >>@@ -213,6 +214,7 @@ static NotifierList machine_init_done_notifiers =
> >> static bool tcg_allowed = true;
> >> bool xen_allowed;
> >>+uint64_t pci_hole_min_size;
> >> uint32_t xen_domid;
> >> enum xen_mode xen_mode = XEN_EMULATE;
> >> static int tcg_tb_size;
> >>@@ -378,6 +380,10 @@ static QemuOptsList qemu_machine_opts = {
> >> .name = "firmware",
> >> .type = QEMU_OPT_STRING,
> >> .help = "firmware image",
> >>+ }, {
> >>+ .name = "pci_hole_min_size",
> >>+ .type = QEMU_OPT_SIZE,
> >>+ .help = "minimum size of PCI mmio hole below 4G",
> >> },
> >> { /* End of list */ }
> >> },
> >
> >Hmm this adds this option to all machine types, doesn't it?
> >But besides xen and i386 machine types, everyone seems to
> >ignore it silently, which seems inelegant.
> >
> >
> >>@@ -4050,6 +4056,16 @@ int main(int argc, char **argv, char **envp)
> >> initrd_filename = qemu_opt_get(machine_opts, "initrd");
> >> kernel_cmdline = qemu_opt_get(machine_opts, "append");
> >> bios_name = qemu_opt_get(machine_opts, "firmware");
> >>+ pci_hole_min_size = qemu_opt_get_size(machine_opts,
> >>+ "pci_hole_min_size",
> >>+ pci_hole_min_size);
> >>+ if (pci_hole_min_size > MAX_PCI_HOLE_SIZE) {
> >>+ fprintf(stderr,
> >>+ "%s: pci_hole_min_size=%llu too big, adjusted to %llu\n",
> >>+ __func__, (unsigned long long) pci_hole_min_size,
> >>+ MAX_PCI_HOLE_SIZE);
> >>+ pci_hole_min_size = MAX_PCI_HOLE_SIZE;
> >>+ }
> >> boot_order = machine->default_boot_order;
> >> opts = qemu_opts_find(qemu_find_opts("boot-opts"), NULL);
> >>diff --git a/xen-all.c b/xen-all.c
> >>index 4a594bd..dbe24c7 100644
> >>--- a/xen-all.c
> >>+++ b/xen-all.c
> >>@@ -155,6 +155,15 @@ qemu_irq *xen_interrupt_controller_init(void)
> >> /* Memory Ops */
> >>+static uint64_t mmio_hole_size(void)
> >>+{
> >>+ uint64_t sz = HVM_BELOW_4G_MMIO_LENGTH;
> >>+ if (sz < pci_hole_min_size) {
> >>+ sz = pci_hole_min_size;
> >>+ }
> >>+ return sz;
> >>+}
> >>+
> >> static void xen_ram_init(ram_addr_t ram_size, MemoryRegion **ram_memory_p)
> >> {
> >> MemoryRegion *sysmem = get_system_memory();
> >>@@ -162,23 +171,20 @@ static void xen_ram_init(ram_addr_t ram_size,
> >>MemoryRegion **ram_memory_p)
> >> ram_addr_t block_len;
> >> block_len = ram_size;
> >>- if (ram_size >= HVM_BELOW_4G_RAM_END) {
> >>- /* Xen does not allocate the memory continuously, and keep a hole
> >>at
> >>- * HVM_BELOW_4G_MMIO_START of HVM_BELOW_4G_MMIO_LENGTH
> >>+ below_4g_mem_size = (1ULL << 32) - mmio_hole_size();
> >>+ if (ram_size < below_4g_mem_size) {
> >>+ below_4g_mem_size = ram_size;
> >>+ } else {
> >>+ above_4g_mem_size = ram_size - below_4g_mem_size;
> >>+ /* Xen does not allocate the memory continuously, and keep a hole
> >>of
> >>+ * size mmio_hole_size().
> >> */
> >>- block_len += HVM_BELOW_4G_MMIO_LENGTH;
> >>+ block_len += mmio_hole_size();
> >> }
> >> memory_region_init_ram(&ram_memory, NULL, "xen.ram", block_len);
> >> *ram_memory_p = &ram_memory;
> >> vmstate_register_ram_global(&ram_memory);
> >>- if (ram_size >= HVM_BELOW_4G_RAM_END) {
> >>- above_4g_mem_size = ram_size - HVM_BELOW_4G_RAM_END;
> >>- below_4g_mem_size = HVM_BELOW_4G_RAM_END;
> >>- } else {
> >>- below_4g_mem_size = ram_size;
> >>- }
> >>-
> >> memory_region_init_alias(&ram_640k, NULL, "xen.ram.640k",
> >> &ram_memory, 0, 0xa0000);
> >> memory_region_add_subregion(sysmem, 0, &ram_640k);
> >>--
> >>1.8.4
> >>
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