KVM: SVM: Move msrpm offset calculation to seperate function

The algorithm to find the offset in the msrpm for a given
msr is needed at other places too. Move that logic to its
own function.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 37 insertions, 16 deletions

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 07437ca12787..429a24435c6d 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -117,6 +117,8 @@ struct vcpu_svm {
         unsigned long int3_rip;
 };
 
+#define MSR_INVALID                     0xffffffffU
+
 /* enable NPT for AMD64 and X86 with PAE */
 #if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE)
 static bool npt_enabled = true;
@@ -200,6 +202,27 @@ static u32 msrpm_ranges[] = {0, 0xc0000000, 0xc0010000};
 #define MSRS_RANGE_SIZE 2048
 #define MSRS_IN_RANGE (MSRS_RANGE_SIZE * 8 / 2)
 
+static u32 svm_msrpm_offset(u32 msr)
+{
+        u32 offset;
+        int i;
+
+        for (i = 0; i < NUM_MSR_MAPS; i++) {
+                if (msr < msrpm_ranges[i] ||
+                    msr >= msrpm_ranges[i] + MSRS_IN_RANGE)
+                        continue;
+
+                offset  = (msr - msrpm_ranges[i]) / 4; /* 4 msrs per u8 */
+                offset += (i * MSRS_RANGE_SIZE);       /* add range offset */
+
+                /* Now we have the u8 offset - but need the u32 offset */
+                return offset / 4;
+        }
+
+        /* MSR not in any range */
+        return MSR_INVALID;
+}
+
 #define MAX_INST_SIZE 15
 
 static inline u32 svm_has(u32 feat)
@@ -418,23 +441,21 @@ err_1:
 static void set_msr_interception(u32 *msrpm, unsigned msr,
                                  int read, int write)
 {
-        int i;
+        u8 bit_read, bit_write;
+        unsigned long tmp;
+        u32 offset;
 
-        for (i = 0; i < NUM_MSR_MAPS; i++) {
-                if (msr >= msrpm_ranges[i] &&
-                    msr < msrpm_ranges[i] + MSRS_IN_RANGE) {
-                        u32 msr_offset = (i * MSRS_IN_RANGE + msr -
-                                          msrpm_ranges[i]) * 2;
-
-                        u32 *base = msrpm + (msr_offset / 32);
-                        u32 msr_shift = msr_offset % 32;
-                        u32 mask = ((write) ? 0 : 2) | ((read) ? 0 : 1);
-                        *base = (*base & ~(0x3 << msr_shift)) |
-                                (mask << msr_shift);
-                        return;
-                }
-        }
-        BUG();
+        offset    = svm_msrpm_offset(msr);
+        bit_read  = 2 * (msr & 0x0f);
+        bit_write = 2 * (msr & 0x0f) + 1;
+        tmp       = msrpm[offset];
+
+        BUG_ON(offset == MSR_INVALID);
+
+        read  ? clear_bit(bit_read,  &tmp) : set_bit(bit_read,  &tmp);
+        write ? clear_bit(bit_write, &tmp) : set_bit(bit_write, &tmp);
+
+        msrpm[offset] = tmp;
 }
 
 static void svm_vcpu_init_msrpm(u32 *msrpm)