[Xen-devel] [PATCH v4 1/8] mtrr: introduce mask to get VCNT from MTRRcap MSR

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

No functional change.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
Changes since v3:
 - Rebase on top of Jan's MTRR fixes.

Changes since v2:
 - Use unsigned int instead of uint8_t in mtrr_pat_not_equal.
---
 xen/arch/x86/cpu/mtrr/main.c    | 2 +-
 xen/arch/x86/hvm/mtrr.c         | 8 ++++----
 xen/include/asm-x86/msr-index.h | 2 ++
 3 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/cpu/mtrr/main.c b/xen/arch/x86/cpu/mtrr/main.c
index 56f71a6e1f..e9df53f00d 100644
--- a/xen/arch/x86/cpu/mtrr/main.c
+++ b/xen/arch/x86/cpu/mtrr/main.c
@@ -95,7 +95,7 @@ static void __init set_num_var_ranges(void)
                config = 2;
        else if (is_cpu(CENTAUR))
                config = 8;
-       num_var_ranges = config & 0xff;
+       num_var_ranges = MASK_EXTR(config, MTRRcap_VCNT);
 }
 
 static void __init init_table(void)
diff --git a/xen/arch/x86/hvm/mtrr.c b/xen/arch/x86/hvm/mtrr.c
index a61cc1e6dc..c298369044 100644
--- a/xen/arch/x86/hvm/mtrr.c
+++ b/xen/arch/x86/hvm/mtrr.c
@@ -78,7 +78,7 @@ static uint8_t __read_mostly pat_entry_tbl[PAT_TYPE_NUMS] =
 bool_t is_var_mtrr_overlapped(const struct mtrr_state *m)
 {
     unsigned int seg, i;
-    unsigned int num_var_ranges = (uint8_t)m->mtrr_cap;
+    unsigned int num_var_ranges = MASK_EXTR(m->mtrr_cap, MTRRcap_VCNT);
 
     for ( i = 0; i < num_var_ranges; i++ )
     {
@@ -193,7 +193,7 @@ static int get_mtrr_type(const struct mtrr_state *m,
    uint8_t     overlap_mtrr = 0;
    uint8_t     overlap_mtrr_pos = 0;
    uint64_t    mask = -(uint64_t)PAGE_SIZE << order;
-   unsigned int seg, num_var_ranges = m->mtrr_cap & 0xff;
+   unsigned int seg, num_var_ranges = MASK_EXTR(m->mtrr_cap, MTRRcap_VCNT);
 
    if ( unlikely(!(m->enabled & 0x2)) )
        return MTRR_TYPE_UNCACHABLE;
@@ -483,7 +483,7 @@ bool mtrr_pat_not_equal(const struct vcpu *vd, const struct 
vcpu *vs)
 
     if ( md->enabled & 2 )
     {
-        unsigned int num_var_ranges = (uint8_t)md->mtrr_cap;
+        unsigned int num_var_ranges = MASK_EXTR(md->mtrr_cap, MTRRcap_VCNT);
 
         /* Test default type MSR. */
         if ( md->def_type != ms->def_type )
@@ -499,7 +499,7 @@ bool mtrr_pat_not_equal(const struct vcpu *vd, const struct 
vcpu *vs)
             return true;
 
         /* Test variable ranges. */
-        if ( num_var_ranges != (uint8_t)ms->mtrr_cap ||
+        if ( num_var_ranges != MASK_EXTR(ms->mtrr_cap, MTRRcap_VCNT) ||
              memcmp(md->var_ranges, ms->var_ranges,
                     num_var_ranges * sizeof(*md->var_ranges)) )
             return true;
diff --git a/xen/include/asm-x86/msr-index.h b/xen/include/asm-x86/msr-index.h
index 8fbccc88a7..95bb66916c 100644
--- a/xen/include/asm-x86/msr-index.h
+++ b/xen/include/asm-x86/msr-index.h
@@ -60,6 +60,8 @@
 #define ATM_LNC_C6_AUTO_DEMOTE         (1UL << 25)
 
 #define MSR_MTRRcap                    0x000000fe
+#define MTRRcap_VCNT                   0x000000ff
+
 #define MSR_IA32_BBL_CR_CTL            0x00000119
 
 #define MSR_IA32_SYSENTER_CS           0x00000174
-- 
2.17.1


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