[Xen-changelog] [xen staging] x86: Improvements to ler debugging

[patchbot@xxxxxxx]

commit 3c675b32720518e87d879f47939b0965d726bab6
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Thu May 24 17:41:53 2018 +0000
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Wed Jul 4 12:12:14 2018 +0100

    x86: Improvements to ler debugging
    
     * Command line documentation for what the option does.
     * Implement a canonicalise_addr() helper and replace the opencoded use in
       sign_extend_msr()
     * Canonicalise the ler pointers and print symbol information.
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
---
 docs/misc/xen-command-line.markdown | 6 ++++++
 xen/arch/x86/hvm/vmx/vmx.c          | 7 +------
 xen/arch/x86/x86_64/traps.c         | 7 ++++++-
 xen/include/asm-x86/x86_64/page.h   | 8 ++++++++
 4 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/docs/misc/xen-command-line.markdown 
b/docs/misc/xen-command-line.markdown
index 8a832c0f8b..4f75f64a90 100644
--- a/docs/misc/xen-command-line.markdown
+++ b/docs/misc/xen-command-line.markdown
@@ -1247,6 +1247,12 @@ if left disabled by the BIOS.
 ### ler (x86)
 > `= <boolean>`
 
+> Default: false
+
+This option is intended for debugging purposes only.  Enable MSR_DEBUGCTL.LBR
+in hypervisor context to be able to dump the Last Interrupt/Exception To/From
+record with other registers.
+
 ### loglvl
 > `= <level>[/<rate-limited level>]` where level is `none | error | warning | 
 > info | debug | all`
 
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index e319bf10ba..4b08439484 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -4182,12 +4182,7 @@ static void sign_extend_msr(u32 msr, int type)
     struct vmx_msr_entry *entry;
 
     if ( (entry = vmx_find_msr(msr, type)) != NULL )
-    {
-        if ( entry->data & VADDR_TOP_BIT )
-            entry->data |= CANONICAL_MASK;
-        else
-            entry->data &= ~CANONICAL_MASK;
-    }
+        entry->data = canonicalise_addr(entry->data);
 }
 
 static void bdw_erratum_bdf14_fixup(void)
diff --git a/xen/arch/x86/x86_64/traps.c b/xen/arch/x86/x86_64/traps.c
index b0401850ef..ed02b788d3 100644
--- a/xen/arch/x86/x86_64/traps.c
+++ b/xen/arch/x86/x86_64/traps.c
@@ -150,7 +150,12 @@ void show_registers(const struct cpu_user_regs *regs)
 
         rdmsrl(ler_msr, from);
         rdmsrl(ler_msr + 1, to);
-        printk("ler: %016lx -> %016lx\n", from, to);
+
+        /* Upper bits may store metadata.  Re-canonicalise for printing. */
+        printk("ler: from %016"PRIx64" [%ps]\n",
+               from, _p(canonicalise_addr(from)));
+        printk("       to %016"PRIx64" [%ps]\n",
+               to, _p(canonicalise_addr(to)));
     }
 }
 
diff --git a/xen/include/asm-x86/x86_64/page.h 
b/xen/include/asm-x86/x86_64/page.h
index 05a0334893..4fe0205553 100644
--- a/xen/include/asm-x86/x86_64/page.h
+++ b/xen/include/asm-x86/x86_64/page.h
@@ -34,6 +34,14 @@
 
 #ifndef __ASSEMBLY__
 
+static inline unsigned long canonicalise_addr(unsigned long addr)
+{
+    if ( addr & VADDR_TOP_BIT )
+        return addr | CANONICAL_MASK;
+    else
+        return addr & ~CANONICAL_MASK;
+}
+
 #include <asm/types.h>
 
 #include <xen/pdx.h>
--
generated by git-patchbot for /home/xen/git/xen.git#staging

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