Jason Baron <jba...@redhat.com> writes: > On Mon, Oct 22, 2012 at 01:40:21PM +0200, Kevin Wolf wrote: >> >> From: Jason Baron <jba...@redhat.com> >> >> >> >> Introduce IF_AHCI so that q35 can differentiate between ide and ahci >> >> disks. >> >> This allows q35 to specify its default disk type. It also allows q35 to >> >> differentiate between ahci and ide disks, such that -drive if=ide does not >> >> result in the creating of an ahci disk. This is important, since >> >> we don't want >> >> to have the meaning of if=ide changing once q35 is introduced. Thus, its >> >> important for this to be applied before we introduce q35.
This isn't the real argument for IF_AHCI. The real argument is that the (bus, unit) namespace for if=ide makes no sense for AHCI. A board can have any number of IDE controllers. Each IDE controller provides one or two buses, and each bus takes up to two units. Together, we get a a board-specific number of buses, where each bus takes up to two units. A board can have any number of AHCI controllers. Each AHCI controller provides a device-specific number of ports. Together, we get a board-specific number of buses, where each bus can takes a bus-specific number of units. Plain q35 doesn't really need to differentiate between IDE and AHCI; it has only AHCI. What it needs is a "one bus with six units" namespace. We could fix this by relaxing if=ide's rigid "two units per bus" for new machine types. You fix it by introducing if=ahci. Probably simpler. But what's the plan for the next generation of controller? Yet another interface type? Note that SCSI suffers from similar rigidity: seven units per bus. That's fine for SCSI-1, but not for some of the other variants. "Differentiate" comes into play when a board sports both AHCI and IDE controllers. Which q35 doesn't, does it? Then, the new if=ahci lets users select the kind of controller more easily than bus numbers would. Drawback: existing command lines upgrade from pc to plain q35 gracefully only if they don't specify if=ide explicitly. Upgrading to some q35 variant with IDE controller on board is even worse: it works, but performance sucks. Some regard this as a feature. >> >> This patch also adds: >> >> >> >> pci_ahci_create_devs(PCIDevice *pci_dev, DriveInfo **hd_table) >> >> >> >> Which provides a convient way of attaching ahci drives to an >> >> ahci controller. >> >> >> >> Reviewed-by: Paolo Bonzini <pbonz...@redhat.com> >> >> Signed-off-by: Jason Baron <jba...@redhat.com> >> >> --- >> > >> > Kevin, could you review/ack this patch pls? >> > >> >> blockdev.c | 13 ++++++++++++- >> >> blockdev.h | 2 ++ >> >> hw/ide.h | 6 ++++++ >> >> hw/ide/ahci.c | 18 ++++++++++++++++++ >> >> hw/ide/core.c | 23 ++++++++++++++++++----- >> >> 5 files changed, 56 insertions(+), 6 deletions(-) >> >> >> >> diff --git a/blockdev.c b/blockdev.c >> >> index c9a49c8..b684348 100644 >> >> --- a/blockdev.c >> >> +++ b/blockdev.c >> >> @@ -33,6 +33,7 @@ static const char *const if_name[IF_COUNT] = { >> >> [IF_SD] = "sd", >> >> [IF_VIRTIO] = "virtio", >> >> [IF_XEN] = "xen", >> >> + [IF_AHCI] = "ahci", >> >> }; >> >> >> >> static const int if_max_devs[IF_COUNT] = { >> >> @@ -52,8 +53,17 @@ static const int if_max_devs[IF_COUNT] = { /* * Do not change these numbers! They govern how drive option * index maps to unit and bus. That mapping is ABI. * * All controllers used to imlement if=T drives need to support * if_max_devs[T] units, for any T with if_max_devs[T] != 0. * Otherwise, some index values map to "impossible" bus, unit * values. * * For instance, if you change [IF_SCSI] to 255, -drive * if=scsi,index=12 no longer means bus=1,unit=5, but * bus=0,unit=12. With an lsi53c895a controller (7 units max), * the drive can't be set up. Regression. >> >> */ >> >> [IF_IDE] = 2, >> >> [IF_SCSI] = 7, >> >> + [IF_AHCI] = 6, >> >> }; >> >> What are the implications of this if we decided to add another AHCI >> controller which had a different number of ports? I suspect that a >> controller with less than 6 ports breaks when you add more drives than a >> single controller can handle, and one with more than 6 ports doesn't use >> up all of its ports before it adds another controller. >> >> Markus? >> > > My plan was to make this field, machine dependent if/when we wanted a > different > size. I don't think it breaks anything to make this change at a later > point. But please correct me, if I am wrong. I'm afraid you are. See the comment immediately above, and commit 27d6bf40. As far as I can see, the least bad solution is leaving if_max_devs[IF_AHCI] zero. Makes index=N an alias for unit=N,bus=0, and leaves rejecting invalid (bus,unit) to the board. >> >> +int get_if_max_devs(BlockInterfaceType if_type) >> >> +{ >> >> + assert(if_type < IF_COUNT); >> >> + assert(if_type >= IF_DEFAULT); >> >> + >> >> + return if_max_devs[if_type]; >> >> +} >> >> if_max_devs has a specific obvious meaning within blockdev.c, but >> outside it's not as obvious. So this function could use a rename. > > ok. No, get rid of it. if_max_devs[]'s purpose is mapping between index and (bus, unit), no more. See below. >> >> /* >> >> * We automatically delete the drive when a device using it gets >> >> * unplugged. Questionable feature, but we can't just drop it. >> >> @@ -518,7 +528,7 @@ DriveInfo *drive_init(QemuOpts *opts, int mach_if) >> >> } else { >> >> /* no id supplied -> create one */ >> >> dinfo->id = g_malloc0(32); >> >> - if (type == IF_IDE || type == IF_SCSI) >> >> + if (type == IF_IDE || type == IF_SCSI || type == IF_AHCI) >> >> mediastr = (media == MEDIA_CDROM) ? "-cd" : "-hd"; >> >> if (max_devs) >> >> snprintf(dinfo->id, 32, "%s%i%s%i", >> >> @@ -550,6 +560,7 @@ DriveInfo *drive_init(QemuOpts *opts, int mach_if) >> >> >> >> switch(type) { >> >> case IF_IDE: >> >> + case IF_AHCI: >> >> case IF_SCSI: >> >> case IF_XEN: >> >> case IF_NONE: >> >> diff --git a/blockdev.h b/blockdev.h >> >> index 8b126ad..bbd1017 100644 >> >> --- a/blockdev.h >> >> +++ b/blockdev.h >> >> @@ -21,6 +21,7 @@ typedef enum { >> >> IF_DEFAULT = -1, /* for use with drive_add() only */ >> >> IF_NONE, >> >> IF_IDE, IF_SCSI, IF_FLOPPY, IF_PFLASH, IF_MTD, IF_SD, IF_VIRTIO, >> >> IF_XEN, >> >> + IF_AHCI, >> >> IF_COUNT >> >> } BlockInterfaceType; >> >> >> >> @@ -56,6 +57,7 @@ static inline int get_mach_if(int mach_if) >> >> return mach_if; >> >> } >> >> >> >> +int get_if_max_devs(BlockInterfaceType if_type); >> >> DriveInfo *drive_get(BlockInterfaceType type, int bus, int unit); >> >> DriveInfo *drive_get_by_index(BlockInterfaceType type, int index); >> >> int drive_get_max_bus(BlockInterfaceType type); >> >> diff --git a/hw/ide.h b/hw/ide.h >> >> index 2db4079..0b7e000 100644 >> >> --- a/hw/ide.h >> >> +++ b/hw/ide.h >> >> @@ -4,6 +4,7 @@ >> >> #include "isa.h" >> >> #include "pci.h" >> >> #include "memory.h" >> >> +#include "blockdev.h" >> >> >> >> #define MAX_IDE_DEVS 2 >> >> >> >> @@ -34,6 +35,11 @@ int ide_get_geometry(BusState *bus, int unit, >> >> int ide_get_bios_chs_trans(BusState *bus, int unit); >> >> >> >> /* ide/core.c */ >> >> +void ata_drive_get(DriveInfo **hd, int max_bus, BlockInterfaceType type); >> >> void ide_drive_get(DriveInfo **hd, int max_bus); >> >> +void ahci_drive_get(DriveInfo **hd, int max_bus); >> >> + >> >> +/* ide/ahci.c */ >> >> +void pci_ahci_create_devs(PCIDevice *pci_dev, DriveInfo **hd_table); Shouldn't this go next to pci_ide_create_devs()'s declaration? Currently in hw/ide/pci.h. >> >> >> >> #endif /* HW_IDE_H */ >> >> diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c >> >> index 68671bc..824b86f 100644 >> >> --- a/hw/ide/ahci.c >> >> +++ b/hw/ide/ahci.c >> >> @@ -26,6 +26,7 @@ >> >> #include <hw/pc.h> >> >> #include <hw/pci.h> >> >> #include <hw/sysbus.h> >> >> +#include <blockdev.h> >> >> >> >> #include "monitor.h" >> >> #include "dma.h" >> >> @@ -1260,3 +1261,20 @@ static void sysbus_ahci_register_types(void) >> >> } >> >> >> >> type_init(sysbus_ahci_register_types) >> >> + >> >> +void pci_ahci_create_devs(PCIDevice *pci_dev, DriveInfo **hd_table) >> >> +{ >> >> + struct AHCIPCIState *dev = DO_UPCAST(struct AHCIPCIState, card, >> >> pci_dev); >> >> + int i; >> >> + DriveInfo *drive; >> >> + >> >> + for (i = 0; i < dev->ahci.ports; i++) { >> >> + if (hd_table[i] == NULL) { >> >> + continue; >> >> + } >> >> + drive = hd_table[i]; >> >> + assert(drive->type == IF_AHCI); >> >> + ide_create_drive(&dev->ahci.dev[i].port, 0, >> >> + hd_table[i]); >> >> + } >> >> +} Shouldn't this go next to pci_ide_create_devs()'s definition? Currently in hw/ide/pci.c. Consider adding a parameter for the number of elements in hd_table[], for robustness. As is, the caller has to ensure hd_table[] has at least dev->ahci.ports elements, which is not obvious from the function signature. >> >> diff --git a/hw/ide/core.c b/hw/ide/core.c >> >> index d683a8c..044da3c 100644 >> >> --- a/hw/ide/core.c >> >> +++ b/hw/ide/core.c >> >> @@ -2341,16 +2341,29 @@ const VMStateDescription vmstate_ide_bus = { >> >> } >> >> }; >> >> >> >> -void ide_drive_get(DriveInfo **hd, int max_bus) >> >> +void ata_drive_get(DriveInfo **hd, int max_bus, BlockInterfaceType type) >> >> Could be static? >> > > Yes. > >> >> { >> >> int i; >> >> + int max_devs; >> >> + >> >> + assert((type == IF_IDE) || type == IF_AHCI); >> >> Interesting use of brackets. > > oops. > >> >> >> >> >> - if (drive_get_max_bus(IF_IDE) >= max_bus) { >> >> + if (drive_get_max_bus(type) >= max_bus) { >> >> fprintf(stderr, "qemu: too many IDE bus: %d\n", max_bus); >> >> "Too many %s buses", type == IF_IDE ? "IDE" : "AHCI" > > ok. > >> >> >> exit(1); >> >> } >> >> - >> >> - for(i = 0; i < max_bus * MAX_IDE_DEVS; i++) { >> >> - hd[i] = drive_get(IF_IDE, i / MAX_IDE_DEVS, i % MAX_IDE_DEVS); >> >> + max_devs = get_if_max_devs(type); >> >> + for (i = 0; i < max_bus * max_devs; i++) { >> >> + hd[i] = drive_get(type, i / max_devs, i % max_devs); >> >> } >> >> } >> >> + >> >> +void ide_drive_get(DriveInfo **hd, int max_bus) >> >> +{ >> >> + ata_drive_get(hd, max_bus, IF_IDE); >> >> +} >> >> + >> >> +void ahci_drive_get(DriveInfo **hd, int max_bus) >> >> +{ >> >> + ata_drive_get(hd, max_bus, IF_AHCI); >> >> +} For IDE, we always have two devices per bus. The boards number of buses varies in theory, and is always two in practice. Thus we have "#define MAX_IDE_DEVS 2" in ide.h, and "#define MAX_IDE_BUS 2" in all the <board>.c. The latter is passed to ide_drive_get() as parameter. Getting the well-known MAX_IDE_DEVS from get_if_max_devs() buys us nothing. For AHCI, I figure we have a device-specific number of ports per device, and a board-specific number of devices (typically one). If there are multiple devices, they don't necessarily sport the same number of ports. Thus, a nested loop does not work. Suggest void ahci_drive_get(DriveInfo **hd, int bus, int max_ports) which the board can call once for each device, with the device's true number of ports as argument. Look ma, no get_if_max_devs()!