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[Xen-devel] [PATCH 07/13] libx86: Introduce a helper to serialise msr_{domain, vcpu}_policy objects



From: Roger Pau Monné <roger.pau@xxxxxxxxxx>

As with CPUID, the an architectural form is used for representing the MSR
data.  It is expected not to change moving forwards, but does have a 32 bit
field (currently reserved) which can be used compatibly if needs be.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Signed-off-by: Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>
Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>
CC: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
---
 tools/include/Makefile             |  1 +
 tools/libxc/Makefile               |  2 +-
 xen/common/libx86/Makefile         |  1 +
 xen/common/libx86/libx86-private.h |  3 ++
 xen/common/libx86/msr.c            | 71 ++++++++++++++++++++++++++++++++++++++
 xen/include/public/arch-x86/xen.h  |  9 ++++-
 xen/include/xen/libx86/msr.h       | 16 +++++++++
 7 files changed, 101 insertions(+), 2 deletions(-)
 create mode 100644 xen/common/libx86/msr.c

diff --git a/tools/include/Makefile b/tools/include/Makefile
index fc99da9..1a0eae7 100644
--- a/tools/include/Makefile
+++ b/tools/include/Makefile
@@ -22,6 +22,7 @@ xen/.dir:
        ln -s ../xen-foreign xen/foreign
        ln -sf $(XEN_ROOT)/xen/include/acpi acpi
 ifeq ($(CONFIG_X86),y)
+       ln -sf $(XEN_ROOT)/xen/include/asm-x86 xen/asm
        ln -sf $(XEN_ROOT)/xen/include/xen/libx86 xen/libx86
 endif
        touch $@
diff --git a/tools/libxc/Makefile b/tools/libxc/Makefile
index f534d90..407a9d1 100644
--- a/tools/libxc/Makefile
+++ b/tools/libxc/Makefile
@@ -83,7 +83,7 @@ $(patsubst %.c,%.opic,$(ELF_SRCS-y)): CFLAGS += 
-Wno-pointer-sign
 # Add libx86 to the build
 vpath %.c ../../xen/common/libx86
 
-GUEST_SRCS-$(CONFIG_X86)     += cpuid.c
+GUEST_SRCS-$(CONFIG_X86)     += cpuid.c msr.c
 
 # new domain builder
 GUEST_SRCS-y                 += xc_dom_core.c xc_dom_boot.c
diff --git a/xen/common/libx86/Makefile b/xen/common/libx86/Makefile
index 3fb2e0b..2f9691e 100644
--- a/xen/common/libx86/Makefile
+++ b/xen/common/libx86/Makefile
@@ -1 +1,2 @@
 obj-y += cpuid.o
+obj-y += msr.o
diff --git a/xen/common/libx86/libx86-private.h 
b/xen/common/libx86/libx86-private.h
index a209850..e4ead1a 100644
--- a/xen/common/libx86/libx86-private.h
+++ b/xen/common/libx86/libx86-private.h
@@ -9,6 +9,7 @@
 #include <xen/types.h>
 
 #include <asm/guest_access.h>
+#include <asm/msr-index.h>
 
 #define copy_to_buffer_offset copy_to_guest_offset
 
@@ -19,6 +20,8 @@
 #include <stdbool.h>
 #include <stddef.h>
 
+#include <xen/asm/msr-index.h>
+
 #include <xen-tools/libs.h>
 
 #define MAX(x, y) ((x) > (y) ? (x) : (y))
diff --git a/xen/common/libx86/msr.c b/xen/common/libx86/msr.c
new file mode 100644
index 0000000..46a3458
--- /dev/null
+++ b/xen/common/libx86/msr.c
@@ -0,0 +1,71 @@
+#include "libx86-private.h"
+
+#include <xen/libx86/msr.h>
+
+/*
+ * Copy a single MSR into the provided msr_entry_buffer_t buffer, performing a
+ * boundary check against the buffer size.
+ */
+static int copy_msr_to_buffer(uint32_t idx, uint64_t val,
+                              msr_entry_buffer_t msrs,
+                              uint32_t *curr_entry, const uint32_t nr_entries)
+{
+    const xen_msr_entry_t ent = { .idx = idx, .val = val };
+
+    if ( *curr_entry == nr_entries )
+        return -ENOBUFS;
+
+    if ( copy_to_buffer_offset(msrs, *curr_entry, &ent, 1) )
+        return -EFAULT;
+
+    ++*curr_entry;
+
+    return 0;
+}
+
+/*
+ * Serialise msr_{domain,vcpu}_policy object into an array.  Writes at most
+ * MSR_MAX_SERIALISED_ENTRIES.  Returns -ENOBUFS if the buffer array is too
+ * short.  On success, nr_entries_p is updated with the actual number of
+ * leaves written.
+ */
+int x86_msr_copy_to_buffer(const struct msr_domain_policy *dp,
+                           const struct msr_vcpu_policy *vp,
+                           msr_entry_buffer_t msrs, uint32_t *nr_entries_p)
+{
+    const uint32_t nr_entries = *nr_entries_p;
+    uint32_t curr_entry = 0;
+
+#define COPY_MSR(idx, val)                                      \
+    ({  int ret;                                                \
+        if ( (ret = copy_msr_to_buffer(                         \
+                  idx, val, msrs, &curr_entry, nr_entries)) )   \
+            return ret;                                         \
+    })
+
+    if ( dp )
+        COPY_MSR(MSR_INTEL_PLATFORM_INFO, dp->plaform_info.raw);
+
+    if ( vp )
+    {
+        COPY_MSR(MSR_SPEC_CTRL, vp->spec_ctrl.raw);
+        COPY_MSR(MSR_INTEL_MISC_FEATURES_ENABLES,
+                 vp->misc_features_enables.raw);
+    }
+
+#undef COPY_MSR
+
+    *nr_entries_p = curr_entry;
+
+    return 0;
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/include/public/arch-x86/xen.h 
b/xen/include/public/arch-x86/xen.h
index f3bdd83..55a149f 100644
--- a/xen/include/public/arch-x86/xen.h
+++ b/xen/include/public/arch-x86/xen.h
@@ -315,7 +315,7 @@ struct xen_arch_domainconfig {
 #endif
 
 /*
- * Representations of architectural CPUID information.  Used as the
+ * Representations of architectural CPUID and MSR information.  Used as the
  * serialised version of Xen's internal representation.
  */
 typedef struct xen_cpuid_leaf {
@@ -325,6 +325,13 @@ typedef struct xen_cpuid_leaf {
 } xen_cpuid_leaf_t;
 DEFINE_XEN_GUEST_HANDLE(xen_cpuid_leaf_t);
 
+typedef struct xen_msr_entry {
+    uint32_t idx;
+    uint32_t flags; /* Reserved MBZ. */
+    uint64_t val;
+} xen_msr_entry_t;
+DEFINE_XEN_GUEST_HANDLE(xen_msr_entry_t);
+
 #endif /* !__ASSEMBLY__ */
 
 /*
diff --git a/xen/include/xen/libx86/msr.h b/xen/include/xen/libx86/msr.h
index 6b8b10b..8776378 100644
--- a/xen/include/xen/libx86/msr.h
+++ b/xen/include/xen/libx86/msr.h
@@ -2,6 +2,10 @@
 #ifndef XEN_LIBX86_MSR_H
 #define XEN_LIBX86_MSR_H
 
+#define MSR_MAX_SERIALISED_ENTRIES              \
+    (1 + /* msr_domain_policy */                \
+     2   /* msr_vcpu_policy*/ )
+
 /* MSR policy object for shared per-domain MSRs */
 struct msr_domain_policy
 {
@@ -45,6 +49,18 @@ struct msr_vcpu_policy
     } misc_features_enables;
 };
 
+#ifdef __XEN__
+#include <public/arch-x86/xen.h>
+typedef XEN_GUEST_HANDLE_64(xen_msr_entry_t) msr_entry_buffer_t;
+#else
+#include <xen/arch-x86/xen.h>
+typedef xen_msr_entry_t *msr_entry_buffer_t;
+#endif
+
+int x86_msr_copy_to_buffer(const struct msr_domain_policy *dp,
+                           const struct msr_vcpu_policy *vp,
+                           msr_entry_buffer_t msrs, uint32_t *nr_entries_p);
+
 #endif /* !XEN_LIBX86_MSR_H */
 
 /*
-- 
2.1.4


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