[Xen-devel] [PATCH 4/6] x86/vvmx: Switch nested MSR intercept handling to use struct vmx_msr_bitmap

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Rename vmx_check_msr_bitmap() to vmx_msr_is_intercepted() in order to more
clearly identify what the boolean return value means.  Change the int
access_type to bool is_write.

The NULL pointer check is moved out, as it doesn't pertain to whether the MSR
is intercepted or not.  The check is moved into nvmx_n2_vmexit_handler(),
where it becomes a hard error in the case that ACTIVATE_MSR_BITMAP is set.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Jun Nakajima <jun.nakajima@xxxxxxxxx>
CC: Kevin Tian <kevin.tian@xxxxxxxxx>
---
 xen/arch/x86/hvm/vmx/vmcs.c        | 31 +++++++++----------------------
 xen/arch/x86/hvm/vmx/vvmx.c        | 23 ++++++++++++-----------
 xen/include/asm-x86/hvm/vmx/vmcs.h |  3 ++-
 3 files changed, 23 insertions(+), 34 deletions(-)

diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
index 0e1a142..f1427f8 100644
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -862,31 +862,18 @@ void vmx_set_msr_intercept(struct vcpu *v, unsigned int 
msr,
         ASSERT(!"MSR out of range for interception\n");
 }
 
-/*
- * access_type: read == 0, write == 1
- */
-int vmx_check_msr_bitmap(unsigned long *msr_bitmap, u32 msr, int access_type)
+bool vmx_msr_is_intercepted(struct vmx_msr_bitmap *msr_bitmap,
+                            unsigned int msr, bool is_write)
 {
-    int ret = 1;
-    if ( !msr_bitmap )
-        return 1;
-
     if ( msr <= 0x1fff )
-    {
-        if ( access_type == 0 )
-            ret = test_bit(msr, msr_bitmap + 0x000/BYTES_PER_LONG); /* 
read-low */
-        else if ( access_type == 1 )
-            ret = test_bit(msr, msr_bitmap + 0x800/BYTES_PER_LONG); /* 
write-low */
-    }
+        return test_bit(msr, is_write ? msr_bitmap->write_low
+                                      : msr_bitmap->read_low);
     else if ( (msr >= 0xc0000000) && (msr <= 0xc0001fff) )
-    {
-        msr &= 0x1fff;
-        if ( access_type == 0 )
-            ret = test_bit(msr, msr_bitmap + 0x400/BYTES_PER_LONG); /* 
read-high */
-        else if ( access_type == 1 )
-            ret = test_bit(msr, msr_bitmap + 0xc00/BYTES_PER_LONG); /* 
write-high */
-    }
-    return ret;
+        return test_bit(msr & 0x1fff, is_write ? msr_bitmap->write_high
+                                               : msr_bitmap->read_high);
+    else
+        /* MSRs outside the bitmap ranges are always intercepted. */
+        return true;
 }
 
 
diff --git a/xen/arch/x86/hvm/vmx/vvmx.c b/xen/arch/x86/hvm/vmx/vvmx.c
index 2c8cf63..0d08789 100644
--- a/xen/arch/x86/hvm/vmx/vvmx.c
+++ b/xen/arch/x86/hvm/vmx/vvmx.c
@@ -2284,22 +2284,23 @@ int nvmx_n2_vmexit_handler(struct cpu_user_regs *regs,
         /* inject to L1 */
         nvcpu->nv_vmexit_pending = 1;
         break;
+
     case EXIT_REASON_MSR_READ:
     case EXIT_REASON_MSR_WRITE:
-    {
-        int status;
         ctrl = __n2_exec_control(v);
-        if ( ctrl & CPU_BASED_ACTIVATE_MSR_BITMAP )
-        {
-            status = vmx_check_msr_bitmap(nvmx->msrbitmap, regs->ecx,
-                         !!(exit_reason == EXIT_REASON_MSR_WRITE));
-            if ( status )
-                nvcpu->nv_vmexit_pending = 1;
-        }
-        else
+
+        /* Without ACTIVATE_MSR_BITMAP, all MSRs are intercepted. */
+        if ( !(ctrl & CPU_BASED_ACTIVATE_MSR_BITMAP) )
             nvcpu->nv_vmexit_pending = 1;
+        else if ( !nvmx->msrbitmap )
+            /* ACTIVATE_MSR_BITMAP set, but L2 bitmap not mapped??? */
+            domain_crash(v->domain);
+        else
+            nvcpu->nv_vmexit_pending =
+                vmx_msr_is_intercepted(nvmx->msrbitmap, regs->ecx,
+                                       exit_reason == EXIT_REASON_MSR_WRITE);
         break;
-    }
+
     case EXIT_REASON_IO_INSTRUCTION:
         ctrl = __n2_exec_control(v);
         if ( ctrl & CPU_BASED_ACTIVATE_IO_BITMAP )
diff --git a/xen/include/asm-x86/hvm/vmx/vmcs.h 
b/xen/include/asm-x86/hvm/vmx/vmcs.h
index 926e792..32a6732 100644
--- a/xen/include/asm-x86/hvm/vmx/vmcs.h
+++ b/xen/include/asm-x86/hvm/vmx/vmcs.h
@@ -543,7 +543,8 @@ int vmx_add_msr(u32 msr, int type);
 void vmx_vmcs_switch(paddr_t from, paddr_t to);
 void vmx_set_eoi_exit_bitmap(struct vcpu *v, u8 vector);
 void vmx_clear_eoi_exit_bitmap(struct vcpu *v, u8 vector);
-int vmx_check_msr_bitmap(unsigned long *msr_bitmap, u32 msr, int access_type);
+bool vmx_msr_is_intercepted(struct vmx_msr_bitmap *msr_bitmap,
+                            unsigned int msr, bool is_write) __nonnull(1);
 void virtual_vmcs_enter(const struct vcpu *);
 void virtual_vmcs_exit(const struct vcpu *);
 u64 virtual_vmcs_vmread(const struct vcpu *, u32 encoding);
-- 
2.1.4


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