[Xen-changelog] [xen master] libx86: Introduce a helper to serialise msr_policy objects

[p***@xen.org]

commit 4874a4db383645ce9f90f56212d679ee0522e5c1
Author: Roger Pau Monné <***@citrix.com>
AuthorDate: Thu Jun 21 16:35:50 2018 +0200
Commit: Andrew Cooper <***@citrix.com>
CommitDate: Tue Nov 6 17:51:18 2018 +0000

libx86: Introduce a helper to serialise msr_policy objects

As with CPUID, 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 <***@citrix.com>
Signed-off-by: Sergey Dyasli <***@citrix.com>
Signed-off-by: Roger Pau Monné <***@citrix.com>
Reviewed-by: Wei Liu <***@citrix.com>
Acked-by: Jan Beulich <***@suse.com>
---
tools/libxc/Makefile | 2 +-
xen/include/public/arch-x86/xen.h | 9 +++++-
xen/include/xen/lib/x86/msr.h | 26 ++++++++++++++++++
xen/lib/x86/Makefile | 1 +
xen/lib/x86/msr.c | 58 +++++++++++++++++++++++++++++++++++++++
xen/lib/x86/private.h | 3 ++
6 files changed, 97 insertions(+), 2 deletions(-)

diff --git a/tools/libxc/Makefile b/tools/libxc/Makefile
index 68bb3679fd..44d9d09d4e 100644
--- a/tools/libxc/Makefile
+++ b/tools/libxc/Makefile
@@ -83,7 +83,7 @@ $(patsubst %.c,%.opic,$(ELF_SRCS-y)): CFLAGS += -Wno-pointer-sign
ifeq ($(CONFIG_X86),y) # Add libx86 to the build
vpath %.c ../../xen/lib/x86

-GUEST_SRCS-y += cpuid.c
+GUEST_SRCS-y += cpuid.c msr.c
endif

# new domain builder
diff --git a/xen/include/public/arch-x86/xen.h b/xen/include/public/arch-x86/xen.h
index 7980f9e584..8ed5904978 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/lib/x86/msr.h b/xen/include/xen/lib/x86/msr.h
index e6b13ad8cb..e2cfbb1a8d 100644
--- a/xen/include/xen/lib/x86/msr.h
+++ b/xen/include/xen/lib/x86/msr.h
@@ -2,6 +2,9 @@
#ifndef XEN_LIB_X86_MSR_H
#define XEN_LIB_X86_MSR_H

+/* Maximum number of MSRs written when serialising msr_policy. */
+#define MSR_MAX_SERIALISED_ENTRIES 1
+
/* MSR policy object for shared per-domain MSRs */
struct msr_policy
{
@@ -22,6 +25,29 @@ struct msr_policy
} plaform_info;
};

+#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
+
+/**
+ * Serialise an msr_policy object into an array.
+ *
+ * @param policy The msr_policy to serialise.
+ * @param msrs The array of msrs to serialise into.
+ * @param nr_entries The number of entries in 'msrs'.
+ * @returns -errno
+ *
+ * Writes at most MSR_MAX_SERIALISED_ENTRIES. May fail with -ENOBUFS if the
+ * buffer array is too short. On success, nr_entries is updated with the
+ * actual number of msrs written.
+ */
+int x86_msr_copy_to_buffer(const struct msr_policy *policy,
+ msr_entry_buffer_t msrs, uint32_t *nr_entries);
+
#endif /* !XEN_LIB_X86_MSR_H */

/*
diff --git a/xen/lib/x86/Makefile b/xen/lib/x86/Makefile
index 3fb2e0bd8f..2f9691e964 100644
--- a/xen/lib/x86/Makefile
+++ b/xen/lib/x86/Makefile
@@ -1 +1,2 @@
obj-y += cpuid.o
+obj-y += msr.o
diff --git a/xen/lib/x86/msr.c b/xen/lib/x86/msr.c
new file mode 100644
index 0000000000..60fb567687
--- /dev/null
+++ b/xen/lib/x86/msr.c
@@ -0,0 +1,58 @@
+#include "private.h"
+
+#include <xen/lib/x86/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;
+}
+
+int x86_msr_copy_to_buffer(const struct msr_policy *p,
+ 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; \
+ })
+
+ COPY_MSR(MSR_INTEL_PLATFORM_INFO, p->plaform_info.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/lib/x86/private.h b/xen/lib/x86/private.h
index 83cb6537ef..3ee99aad62 100644
--- a/xen/lib/x86/private.h
+++ b/xen/lib/x86/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>

static inline bool test_bit(unsigned int bit, const void *vaddr)
--
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