[Xen-devel] [RFC v2] misc/xenmicrocode: Upload /lib/firmware/<some blob> to the hypervisor

["Luis R. Rodriguez" <mcgrof@xxxxxxxxxxxxxxxx>]

From: "Luis R. Rodriguez" <mcgrof@xxxxxxxx>

There are several ways that a Xen system can update the
CPU microcode on a pvops kernel [0] now, the preferred way
is through the early microcode update mechanism. At run
time folks should use this new xenmicrocode tool and use
the same CPU microcode file as present on /lib/firmware.

Some distributions may use the historic sysfs rescan interface,
users of that mechanism should be aware that the interface will
not be available when using Xen and as such should first check
the presence of the interface before usage, as an alternative
this xenmicrocode tool can be used on priviledged domains.

Folks wishing to update CPU microcode at run time should be
aware that not all CPU microcode can be updated on a system
and should take care to ensure that only known-to-work and
supported CPU microcode updates are used [0]. To avoid issues
with delays on the hypercall / microcode update this
implementation will quiesce all domains prior to updating
the microcode, and then only queisce'd domains will be
unpaused once done.

[0] http://wiki.xenproject.org/wiki/XenParavirtOps/microcode_update

Based on original work by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Takashi Iwai <tiwai@xxxxxxx>
Cc: Olaf Hering <ohering@xxxxxxx>
Cc: Jan Beulich <JBeulich@xxxxxxxx>
Cc: Jason Douglas <jdouglas@xxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Michal Marek <mmarek@xxxxxxx>
Cc: Henrique de Moraes Holschuh <hmh@xxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxx>
---

Just wrote this, haven't tested it. This does some queiscing prior
to doing the microcode update. The quiescing is done by pausing
all domains. Once the microcode update is done we only unpause
domains which we queisced as part of our work. Let me know if this
is on the right track to help avoid issues noted on the list.

 tools/libxc/include/xenctrl.h |   2 +
 tools/libxc/xc_misc.c         | 102 ++++++++++++++++++++++++++++++++++++++++++
 tools/misc/Makefile           |   4 ++
 tools/misc/xenmicrocode.c     | 101 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 209 insertions(+)
 create mode 100644 tools/misc/xenmicrocode.c

diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
index 0ad8b8d..d5db0b8 100644
--- a/tools/libxc/include/xenctrl.h
+++ b/tools/libxc/include/xenctrl.h
@@ -55,6 +55,7 @@
 #include <xen/foreign/x86_32.h>
 #include <xen/foreign/x86_64.h>
 #include <xen/arch-x86/xen-mca.h>
+#include <xen/platform.h>
 #endif
 
 #define XC_PAGE_SHIFT           12
@@ -2145,6 +2146,7 @@ int xc_cpuid_apply_policy(xc_interface *xch,
 void xc_cpuid_to_str(const unsigned int *regs,
                      char **strs); /* some strs[] may be NULL if ENOMEM */
 int xc_mca_op(xc_interface *xch, struct xen_mc *mc);
+int xc_microcode_update(xc_interface *xch, uint8_t *fbuf, size_t len);
 #endif
 
 struct xc_px_val {
diff --git a/tools/libxc/xc_misc.c b/tools/libxc/xc_misc.c
index e253a58..6137e24 100644
--- a/tools/libxc/xc_misc.c
+++ b/tools/libxc/xc_misc.c
@@ -20,6 +20,7 @@
 
 #include "xc_private.h"
 #include <xen/hvm/hvm_op.h>
+#include <xen/platform.h>
 
 int xc_get_max_cpus(xc_interface *xch)
 {
@@ -250,6 +251,107 @@ int xc_mca_op(xc_interface *xch, struct xen_mc *mc)
     xc_hypercall_bounce_post(xch, mc);
     return ret;
 }
+
+struct xc_quiesce_request {
+    int num_quiesced;
+    int domids[1024]; /* never domid 0 */
+};
+
+/*
+ * Do not pause already paused domains, and allow us to
+ * unpause only quiesced domains.
+ */
+static int quiesce_all_domains(xc_interface *xch,
+                              struct xc_quiesce_request *quiesce_request)
+{
+    xc_domaininfo_t info[1024];
+    int i, nb_domain;
+
+    nb_domain = xc_domain_getinfolist(xch, 0, 1024, info);
+    if ( nb_domain < 0 )
+    {
+       return -1;
+    }
+
+    for ( i = 0; i < nb_domain; i++ )
+    {
+        if ( info[i].domain == 0 )
+               continue;
+       if ( info[i].flags & XEN_DOMINF_paused )
+               continue;
+
+        xc_domain_pause(xch, info[i].domain);
+
+       quiesce_request->domids[quiesce_request->num_quiesced] = info[i].domain;
+       quiesce_request->num_quiesced++;
+    }
+
+    return 0;
+}
+
+static void unquiesce_all_domains(xc_interface *xch,
+                                  struct xc_quiesce_request *quiesce_request)
+{
+    int i;
+
+    for ( i = 0; i < quiesce_request->num_quiesced; i++ )
+    {
+       xc_domain_unpause(xch, quiesce_request->domids[i]);
+    }
+}
+
+int xc_microcode_update(xc_interface *xch, uint8_t *fbuf, size_t len)
+{
+    int ret = 0;
+    DECLARE_HYPERCALL_BUFFER(struct xenpf_microcode_update, uc);
+    DECLARE_HYPERCALL;
+    struct xen_platform_op op_s;
+    struct xen_platform_op *op = &op_s;
+    DECLARE_HYPERCALL_BOUNCE(op, sizeof(*op), XC_HYPERCALL_BUFFER_BOUNCE_BOTH);
+    struct xc_quiesce_request quiesce_request;
+
+    memset(&quiesce_request, 0, sizeof(struct xc_quiesce_request));
+
+    if ( !xch )
+    {
+        return -1;
+    }
+
+    uc = xc_hypercall_buffer_alloc(xch, uc, len);
+    if ( uc == NULL )
+    {
+        PERROR("Could not allocate memory for xc_microcode_update hypercall");
+        return -1;
+    }
+
+    memcpy(uc, fbuf, len);
+
+    set_xen_guest_handle(op->u.microcode.data, uc);
+    op->cmd = XENPF_microcode_update;
+    op->interface_version = XENPF_INTERFACE_VERSION;
+    op->u.microcode.length = len;
+
+    if ( xc_hypercall_bounce_pre(xch, op) )
+    {
+       xc_hypercall_buffer_free(xch, uc);
+        PERROR("Could not bounce memory for xc_microcode_update hypercall");
+        return -1;
+    }
+
+    hypercall.op = __HYPERVISOR_platform_op;
+    hypercall.arg[0] = HYPERCALL_BUFFER_AS_ARG(op);
+
+    quiesce_all_domains(xch, &quiesce_request);
+    ret = do_xen_hypercall(xch, &hypercall);
+    unquiesce_all_domains(xch, &quiesce_request);
+
+    xc_hypercall_bounce_post(xch, op);
+    xc_hypercall_buffer_free(xch, uc);
+    xc_interface_close(xch);
+
+    return ret;
+}
+
 #endif
 
 int xc_perfc_reset(xc_interface *xch)
diff --git a/tools/misc/Makefile b/tools/misc/Makefile
index a255c22..ba4779a 100644
--- a/tools/misc/Makefile
+++ b/tools/misc/Makefile
@@ -21,6 +21,7 @@ INSTALL_SBIN-$(CONFIG_X86)     += xen-hvmcrash
 INSTALL_SBIN-$(CONFIG_X86)     += xen-hvmctx
 INSTALL_SBIN-$(CONFIG_X86)     += xen-lowmemd
 INSTALL_SBIN-$(CONFIG_X86)     += xen-mfndump
+INSTALL_SBIN-$(CONFIG_X86)     += xenmicrocode
 INSTALL_SBIN                   += xen-ringwatch
 INSTALL_SBIN                   += xen-tmem-list-parse
 INSTALL_SBIN                   += xencov
@@ -74,6 +75,9 @@ xenperf: xenperf.o
 xenpm: xenpm.o
        $(CC) $(LDFLAGS) -o $@ $< $(LDLIBS_libxenctrl) $(APPEND_LDFLAGS)
 
+xenmicrocode: xenmicrocode.o
+       $(CC) $(LDFLAGS) -o $@ $< $(LDLIBS_libxenctrl) $(APPEND_LDFLAGS)
+
 gtracestat: gtracestat.o
        $(CC) $(LDFLAGS) -o $@ $< $(APPEND_LDFLAGS)
 
diff --git a/tools/misc/xenmicrocode.c b/tools/misc/xenmicrocode.c
new file mode 100644
index 0000000..d027b13
--- /dev/null
+++ b/tools/misc/xenmicrocode.c
@@ -0,0 +1,101 @@
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <errno.h>
+#include <string.h>
+#include <inttypes.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <xenctrl.h>
+
+/*
+ * Documentation:
+ *
+ * http://wiki.xenproject.org/wiki/XenParavirtOps/microcode_update
+ */
+
+void show_help(void)
+{
+    fprintf(stderr,
+            "xenmicrocode: Xen runtime CPU microcode update tool\n"
+            "Usage: xenmicrocode </lib/firmware/microcode-file>\n"
+           );
+}
+
+int main(int argc, char *argv[])
+{
+    int fd = 0;
+    uint8_t *fbuf;
+    char *filename;
+    struct stat buf;
+    static xc_interface *xch;
+    int ret;
+
+    if ( argc != 2 )
+    {
+       show_help();
+       return 1;
+    }
+
+    if ( !strcmp("--help", argv[1]) ||
+         !strcmp("-h", argv[1]) )
+    {
+       show_help();
+        return 1;
+    }
+
+    /* microcode file as present on /lib/firmware/ */
+    filename = argv[1];
+
+    fd = open(filename, O_RDONLY);
+    if ( fd <= 0 )
+    {
+       show_help();
+        fprintf(stderr,
+                "Could not open; err: %d(%s)\n", errno, strerror(errno));
+        return errno;
+    }
+
+    if ( stat(filename, &buf) != 0 )
+    {
+        fprintf(stderr, "Could not open; err: %d(%s)\n", errno, 
strerror(errno));
+        close(fd);
+        return errno;
+    }
+
+    xch = xc_interface_open(0,0,0);
+    if ( !xch )
+    {
+        close(fd);
+        fprintf(stderr, "failed to get the handler\n");
+        return 1;
+    }
+
+    printf("%s: %ld\n", filename, buf.st_size);
+
+    fbuf = mmap(0, buf.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
+    if ( fbuf == MAP_FAILED )
+    {
+        fprintf(stderr, "Could not map: error: %d(%s)\n", errno,
+                strerror(errno));
+        close(fd);
+        return errno;
+    }
+
+    ret = xc_microcode_update(xch, fbuf, buf.st_size);
+
+    if ( munmap(fbuf, buf.st_size) )
+    {
+        fprintf(stderr, "Could not unmap: %d(%s)\n", errno, strerror(errno));
+        close(fd);
+        return errno;
+    }
+
+    close(fd);
+
+    return ret;
+}
-- 
2.1.1


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