[Xen-devel] [PATCH v2 2/6] 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>
---
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/cpu/mtrr/main.c    | 2 +-
 xen/arch/x86/hvm/mtrr.c         | 6 +++---
 xen/include/asm-x86/msr-index.h | 2 ++
 3 files changed, 6 insertions(+), 4 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 b3c08c3977..bdff56a912 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;
@@ -478,7 +478,7 @@ bool_t mtrr_pat_not_equal(struct vcpu *vd, struct vcpu *vs)
     struct mtrr_state *md = &vd->arch.hvm_vcpu.mtrr;
     struct mtrr_state *ms = &vs->arch.hvm_vcpu.mtrr;
     int32_t res;
-    uint8_t num_var_ranges = (uint8_t)md->mtrr_cap;
+    uint8_t num_var_ranges = MASK_EXTR(md->mtrr_cap, MTRRcap_VCNT);
 
     /* Test fixed ranges. */
     res = memcmp(md->fixed_ranges, ms->fixed_ranges,
diff --git a/xen/include/asm-x86/msr-index.h b/xen/include/asm-x86/msr-index.h
index 6d94d65575..f385fbdc73 100644
--- a/xen/include/asm-x86/msr-index.h
+++ b/xen/include/asm-x86/msr-index.h
@@ -58,6 +58,8 @@
 #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
-- 
2.17.0


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