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Re: [Xen-devel] Fwd: Fwd: [Xen-users] Shared memory between Dom0 and Dom

To: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Subject: Re: [Xen-devel] Fwd: Fwd: [Xen-users] Shared memory between Dom0 and DomU
From: Pasi Kärkkäinen <pasik@xxxxxx>
Date: Wed, 16 Mar 2011 09:58:47 +0200
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, MAYAP christine <christine.mayapkamga@xxxxxxxxxxx>, xen-users@xxxxxxxxxxxxxxxxxxx
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On Tue, Mar 15, 2011 at 11:17:14PM -0400, Konrad Rzeszutek Wilk wrote:
> On Thu, Mar 10, 2011 at 11:03:25AM +0100, MAYAP christine wrote:
> > Hello,
> > 
> > I'm still reading document about inter-VM communication via shared memory.
> > I found many reference about IVC.
> 
> The IVC on I think is the XCP source code. Google for XCP source code
> and you should find it.
> 

There's also V4V in Citrix XenClient.. sources available in the source iso.
It includes xen patches, linux kernel patches, and user space libraries 
providing a socket-like API (for linux and windows).

-- Pasi

> > Is it already present in Xen? How can i use them?
> 
> You could also look at gntalloc driver.
> Look in git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git #master 
> tree.
> 
> 
> I think it pretty much does what you want. Here is test code that
> you can use to communicate between domains using mmap-ed memory.
> 
> 
> Courtesy of Daniel De Graaf.
> 
> #include <errno.h>
> #include <fcntl.h>
> #include <unistd.h>
> #include <stdio.h>
> #include <string.h>
> #include <stdint.h>
> #include <sys/ioctl.h>
> #include <sys/mman.h>
> 
> struct ioctl_gntdev_grant_ref {
>       /* The domain ID of the grant to be mapped. */
>       uint32_t domid;
>       /* The grant reference of the grant to be mapped. */
>       uint32_t ref;
> };
> 
> /*
>  * Allocates a new page and creates a new grant reference.
>  */
> #define IOCTL_GNTALLOC_ALLOC_GREF \
> _IOC(_IOC_NONE, 'G', 5, sizeof(struct ioctl_gntalloc_alloc_gref))
> struct ioctl_gntalloc_alloc_gref {
>       /* IN parameters */
>       /* The ID of the domain to be given access to the grants. */
>       uint16_t domid;
>       /* Flags for this mapping */
>       uint16_t flags;
>       /* Number of pages to map */
>       uint32_t count;
>       /* OUT parameters */
>       /* The offset to be used on a subsequent call to mmap(). */
>       uint64_t index;
>       /* The grant references of the newly created grant, one per page */
>       /* Variable size, depending on count */
>       uint32_t gref_ids[1];
> };
> 
> #define GNTALLOC_FLAG_WRITABLE 1
> 
> /*
>  * Deallocates the grant reference, allowing the associated page to be freed 
> if
>  * no other domains are using it.
>  */
> #define IOCTL_GNTALLOC_DEALLOC_GREF \
> _IOC(_IOC_NONE, 'G', 6, sizeof(struct ioctl_gntalloc_dealloc_gref))
> struct ioctl_gntalloc_dealloc_gref {
>       /* IN parameters */
>       /* The offset returned in the map operation */
>       uint64_t index;
>       /* Number of references to unmap */
>       uint32_t count;
> };
> 
> #define IOCTL_GNTDEV_MAP_GRANT_REF \
> _IOC(_IOC_NONE, 'G', 0, sizeof(struct ioctl_gntdev_map_grant_ref))
> struct ioctl_gntdev_map_grant_ref {
>     /* IN parameters */
>     /* The number of grants to be mapped. */
>     uint32_t count;
>     uint32_t pad;
>     /* OUT parameters */
>     /* The offset to be used on a subsequent call to mmap(). */
>     uint64_t index;
>     /* Variable IN parameter. */
>     /* Array of grant references, of size @count. */
>     struct ioctl_gntdev_grant_ref refs[1];
> };
> #define GNTDEV_MAP_WRITABLE 0x1
> 
> #define IOCTL_GNTDEV_UNMAP_GRANT_REF \
> _IOC(_IOC_NONE, 'G', 1, sizeof(struct ioctl_gntdev_unmap_grant_ref))       
> struct ioctl_gntdev_unmap_grant_ref {
>     /* IN parameters */
>     /* The offset was returned by the corresponding map operation. */
>     uint64_t index;
>     /* The number of pages to be unmapped. */
>     uint32_t count;
>     uint32_t pad;
> };
> 
> /*
>  * Sets up an unmap notification within the page, so that the other side can 
> do
>  * cleanup if this side crashes. Required to implement cross-domain robust
>  * mutexes or close notification on communication channels.
>  *
>  * Each mapped page only supports one notification; multiple calls referring 
> to
>  * the same page overwrite the previous notification. You must clear the
>  * notification prior to the IOCTL_GNTALLOC_DEALLOC_GREF if you do not want it
>  * to occur.
>  */
> #define IOCTL_GNTDEV_SET_UNMAP_NOTIFY \
> _IOC(_IOC_NONE, 'G', 7, sizeof(struct ioctl_gntdev_unmap_notify))
> struct ioctl_gntdev_unmap_notify {
>       /* IN parameters */
>       /* Index of a byte in the page */
>       uint64_t index;
>       /* Action(s) to take on unmap */
>       uint32_t action;
>       /* Event channel to notify */
>       uint32_t event_channel_port;
> };
> 
> /* Clear (set to zero) the byte specified by index */
> #define UNMAP_NOTIFY_CLEAR_BYTE 0x1
> /* Send an interrupt on the indicated event channel */
> #define UNMAP_NOTIFY_SEND_EVENT 0x2
> 
> /*
>  * Sets up an unmap notification within the page, so that the other side can 
> do
>  * cleanup if this side crashes. Required to implement cross-domain robust
>  * mutexes or close notification on communication channels.
>  *
>  * Each mapped page only supports one notification; multiple calls referring 
> to
>  * the same page overwrite the previous notification. You must clear the
>  * notification prior to the IOCTL_GNTALLOC_DEALLOC_GREF if you do not want it
>  * to occur.
>  */
> #define IOCTL_GNTALLOC_SET_UNMAP_NOTIFY \
> _IOC(_IOC_NONE, 'G', 7, sizeof(struct ioctl_gntalloc_unmap_notify))
> struct ioctl_gntalloc_unmap_notify {
>       /* IN parameters */
>       /* Index of a byte in the page */
>       uint64_t index;
>       /* Action(s) to take on unmap */
>       uint32_t action;
>       /* Event channel to notify */
>       uint32_t event_channel_port;
> };
> 
> /* Clear (set to zero) the byte specified by index */
> #define UNMAP_NOTIFY_CLEAR_BYTE 0x1
> /* Send an interrupt on the indicated event channel */
> #define UNMAP_NOTIFY_SEND_EVENT 0x2
> 
> #ifndef offsetof
> #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
> #endif
> 
> 
> int a_fd;
> int d_fd;
> 
> struct shr_page {
>       uint64_t id;
>       char buffer[64];
>       uint8_t notifies[8];
> };
> 
> struct data {
>       struct shr_page* mem;
>       int handle;
> } items[128];
> 
> void sa(int id)
> {
>       struct ioctl_gntalloc_alloc_gref arg = {
>               .domid = id,
>               .flags = GNTALLOC_FLAG_WRITABLE,
>               .count = 1
>       };
>       int rv = ioctl(a_fd, IOCTL_GNTALLOC_ALLOC_GREF, &arg);
>       if (rv) {
>               printf("src-add error: %s (rv=%d)\n", strerror(errno), rv);
>               return;
>       }
>       int i=0;
>       while (items[i].mem) i++;
>       items[i].mem = mmap(0, 4096, PROT_READ|PROT_WRITE, MAP_SHARED, a_fd, 
> arg.index);
>       if (items[i].mem == MAP_FAILED) {
>               items[i].mem = 0;
>               printf("mmap failed: SHOULD NOT HAPPEN\n");
>               return;
>       }
>       items[i].handle = arg.index;
>       printf("Created shared page with domain %d, grant #%d. Mapped locally 
> at %d=%p\n",
>               id, arg.gref_ids[0], arg.index, items[i].mem);
> 
>       items[i].mem->id = rand() | ((long)(getpid()) << 32);
>       items[i].mem->notifies[0] = 1;
>       struct ioctl_gntalloc_unmap_notify uarg = {
>               .index = arg.index + offsetof(struct shr_page, notifies[0]),
>               .action = UNMAP_NOTIFY_CLEAR_BYTE
>       };
>       rv = ioctl(a_fd, IOCTL_GNTALLOC_SET_UNMAP_NOTIFY, &uarg);
>       if (rv)
>               printf("gntalloc unmap notify error: %s (rv=%d)\n", 
> strerror(errno), rv);
> }
> 
> void sd(int ref) {
>       struct ioctl_gntalloc_dealloc_gref arg = {
>               .index = ref,
>               .count = 1
>       };
> 
>       int rv = ioctl(a_fd, IOCTL_GNTALLOC_DEALLOC_GREF, &arg);
>       if (rv)
>               printf("src-del error: %s (rv=%d)\n", strerror(errno), rv);
>       else
>               printf("Stopped offering grant at offset %d\n", ref);
> }
> 
> void mm(int domid, int refid) {
>       struct ioctl_gntdev_map_grant_ref arg = {
>               .count = 1,
>               .refs[0].domid = domid,
>               .refs[0].ref = refid,
>       };
>       int rv = ioctl(d_fd, IOCTL_GNTDEV_MAP_GRANT_REF, &arg);
>       if (rv) {
>               printf("Could not map grant %d.%d: %s (rv=%d)\n", domid, refid, 
> strerror(errno), rv);
>               return;
>       }
>       int i=0,j=1;
>       while (items[i].mem) i++;
>       items[i].mem = mmap(0, 4096, PROT_READ|PROT_WRITE, MAP_SHARED, d_fd, 
> arg.index);
>       if (items[i].mem == MAP_FAILED) {
>               items[i].mem = 0;
>               printf("Could not map grant %d.%d: %s (map failed)\n", domid, 
> refid, strerror(errno), rv);
>               return;
>       }
>       items[i].handle = arg.index;
>       printf("Mapped grant %d.%d as %d=%p\n", domid, refid, arg.index, 
> items[i].mem);
> 
>       while (items[i].mem->notifies[j]) j++;
>       items[i].mem->notifies[j] = 1;
>       struct ioctl_gntalloc_unmap_notify uarg = {
>               .index = arg.index + offsetof(struct shr_page, notifies[j]),
>               .action = UNMAP_NOTIFY_CLEAR_BYTE
>       };
>       rv = ioctl(d_fd, IOCTL_GNTDEV_SET_UNMAP_NOTIFY, &uarg);
>       if (rv)
>               printf("gntdev unmap notify error: %s (rv=%d)\n", 
> strerror(errno), rv);
> }
> 
> void gu(int index) {
>       struct ioctl_gntdev_unmap_grant_ref arg = {
>               .index = index,
>               .count = 1,
>       };
>       int rv = ioctl(d_fd, IOCTL_GNTDEV_UNMAP_GRANT_REF, &arg);
>       if (rv)
>               printf("gu error: %s (rv=%d)\n", strerror(errno), rv);
>       else
>               printf("Unhooked mapped grant at offset %d\n", index);
> }
> 
> void mu(void* addr) {
>       int i = 0;
>       munmap(addr, 4096);
>       while (i < 128)
>       {
>               if (items[i].mem == addr)
>                       items[i].mem = 0;
>               i++;
>       }
>       printf("Unmapped page at %p\n", addr);
> }
> 
> void show(char* word) {
>       int i;
>       int wlen = strlen(word);
>       for(i=0; i < 128; i++) {
>               if (!items[i].mem)
>                       continue;
>               memmove(items[i].mem->buffer + wlen, items[i].mem->buffer, 63 - 
> wlen);
>               memcpy(items[i].mem->buffer, word, wlen);
>               printf("%02d(%ld,%d): id %16lx n=%d%d%d%d%d%d%d%d b=%s\n",
>                       i, items[i].mem, items[i].handle, items[i].mem->id,
>                       items[i].mem->notifies[0], items[i].mem->notifies[1], 
> items[i].mem->notifies[2], items[i].mem->notifies[3], 
>                       items[i].mem->notifies[4], items[i].mem->notifies[5], 
> items[i].mem->notifies[6], items[i].mem->notifies[7], 
>                       items[i].mem->buffer);
>       }
>       printf("END\n");
> }
> 
> int main(int argc, char** argv) {
>       a_fd = open("/dev/xen/gntalloc", O_RDWR);
>       d_fd = open("/dev/xen/gntdev", O_RDWR);
>       printf(
>               "add <domid>           return gntref, address\n"
>               "map <domid> <ref>     return index, address\n"
>               "adel <gntref>         delete <add> internal\n"
>               "ddel <index>          delete <map> internal\n"
>               "unmap <address>       unmap memory\n"
>               "show                  show all pages\n"
>               "<word>                append word to all mapped pages, show\n"
>               " PID %x\n", getpid()
>       );
>       while (1) {
>               char line[80];
>               char word[80];
>               long a, b;
>               printf("\n> ");
>               fflush(stdout);
>               fgets(line, 80, stdin);
>               sscanf(line, "%s %ld %ld", word, &a, &b);
>               if (!strcmp(word, "add")) {
>                       sa(a);
>               } else if (!strcmp(word, "map")) {
>                       mm(a, b);
>               } else if (!strcmp(word, "adel")) {
>                       sd(a);
>               } else if (!strcmp(word, "ddel")) {
>                       gu(a);
>               } else if (!strcmp(word, "unmap")) {
>                       mu((void*)a);
>               } else if (!strcmp(word, "show")) {
>                       show("");
>               } else {
>                       show(word);
>               }
>       }
> }
> > 
> > I really need some explanations .
> > Thanks!
> > 
> > 
> > 
> > -------- Message original --------
> > Sujet:      Fwd: [Xen-users] Shared memory between Dom0 and DomU
> > Date :      Wed, 09 Mar 2011 15:12:06 +0100
> > De :        MAYAP christine <christine.mayapkamga@xxxxxxxxxxx>
> > Pour :      xen-devel@xxxxxxxxxxxxxxxxxxx, xen-users@xxxxxxxxxxxxxxxxxxx
> > 
> > 
> > 
> > Hello
> > 
> > While waiting for some help, i continued to google about this topic.
> > In fact, i want two distinct process (one on the Dom0 and the second
> > one on the DomU) to be able the read or write in a share memory.
> > 
> > Many post are talking about granting permissions or grant table.
> > 
> > I'm sorry if my question is a bit stupid. Where would i start to be
> > able the test those grant permission?
> > Should i need to write an external program or should i modify some
> > Xen source codes?
> > 
> > I really have no idea about where to start.
> > I'll sincerely appreciate any idea. Even one stating where to start.
> > 
> > Thanks in advance!
> > 
> > -------- Message original --------
> > Sujet:      [Xen-users] Shared memory between Dom0 and DomU
> > Date :      Wed, 09 Mar 2011 13:07:19 +0100
> > De :        MAYAP christine <christine.mayapkamga@xxxxxxxxxxx>
> > Pour :      xen-devel@xxxxxxxxxxxxxxxxxxx, xen-users@xxxxxxxxxxxxxxxxxxx
> > 
> > 
> > 
> > HI,
> > 
> > I'm a newbie in using shared memory with Xen. I was usually unsing it
> > between process on a same Computer.
> > 
> > Please, can i have some usefull links abour sharing memoru betwen Dom0
> > and DomU first and between DomU.
> > 
> > I'm able to give more informations if needed!
> > 
> > Cheers!
> > 
> > -- 
> > MAYAP Christine
> > IRIT/ENSEEIHT
> > 2 rue Charles Camichel - BP 7122
> > 31071 Toulouse cedex  7
> > 
> > 
> > _______________________________________________
> > Xen-users mailing list
> > Xen-users@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-users
> > 
> 
> > _______________________________________________
> > Xen-users mailing list
> > Xen-users@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-users
> 
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
> 
> 
> _______________________________________________
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