x86: fix (and simplify) MTRR overlap checking Obtaining one individual range per variable range register (via get_mtrr_range()) was bogus from the beginning, as these registers may cover multiple disjoint ranges. Do away with that, in favor of simply comparing masked addresses. Also, for is_var_mtrr_overlapped()'s result to be correct when called from mtrr_wrmsr(), generic_set_mtrr() must update saved state first. As minor cleanup changes, constify is_var_mtrr_overlapped()'s parameter and make mtrr_wrmsr() static. Signed-off-by: Jan Beulich --- a/xen/arch/x86/cpu/mtrr/generic.c +++ b/xen/arch/x86/cpu/mtrr/generic.c @@ -220,7 +220,7 @@ void __init mtrr_state_warn(void) /* Doesn't attempt to pass an error out to MTRR users because it's quite complicated in some cases and probably not worth it because the best error handling is to ignore it. */ -void mtrr_wrmsr(unsigned int msr, uint64_t msr_content) +static void mtrr_wrmsr(unsigned int msr, uint64_t msr_content) { if (wrmsr_safe(msr, msr_content) < 0) printk(KERN_ERR @@ -495,8 +495,8 @@ static void generic_set_mtrr(unsigned in if (size == 0) { /* The invalid bit is kept in the mask, so we simply clear the relevant mask register to disable a range. */ + memset(vr, 0, sizeof(*vr)); mtrr_wrmsr(MSR_IA32_MTRR_PHYSMASK(reg), 0); - memset(vr, 0, sizeof(struct mtrr_var_range)); } else { uint32_t base_lo, base_hi, mask_lo, mask_hi; --- a/xen/arch/x86/cpu/mtrr/mtrr.h +++ b/xen/arch/x86/cpu/mtrr/mtrr.h @@ -63,7 +63,6 @@ extern const struct mtrr_ops *mtrr_if; extern unsigned int num_var_ranges; void mtrr_state_warn(void); -void mtrr_wrmsr(unsigned int msr, uint64_t msr_content); extern int amd_init_mtrr(void); extern int cyrix_init_mtrr(void); --- a/xen/arch/x86/hvm/mtrr.c +++ b/xen/arch/x86/hvm/mtrr.c @@ -26,8 +26,6 @@ #include #include -static uint32_t size_or_mask; - /* Get page attribute fields (PAn) from PAT MSR. */ #define pat_cr_2_paf(pat_cr,n) ((((uint64_t)pat_cr) >> ((n)<<3)) & 0xff) @@ -77,61 +75,28 @@ static uint8_t __read_mostly mtrr_epat_t static uint8_t __read_mostly pat_entry_tbl[PAT_TYPE_NUMS] = { [0 ... PAT_TYPE_NUMS-1] = INVALID_MEM_TYPE }; -static void get_mtrr_range(uint64_t base_msr, uint64_t mask_msr, - uint64_t *base, uint64_t *end) +bool_t is_var_mtrr_overlapped(const struct mtrr_state *m) { - uint32_t mask_lo = (uint32_t)mask_msr; - uint32_t mask_hi = (uint32_t)(mask_msr >> 32); - uint32_t base_lo = (uint32_t)base_msr; - uint32_t base_hi = (uint32_t)(base_msr >> 32); - uint32_t size; - - if ( !(mask_lo & MTRR_PHYSMASK_VALID) ) - { - /* Invalid (i.e. free) range */ - *base = 0; - *end = 0; - return; - } - - /* Work out the shifted address mask. */ - mask_lo = (size_or_mask | (mask_hi << (32 - PAGE_SHIFT)) | - (mask_lo >> PAGE_SHIFT)); - - /* This works correctly if size is a power of two (a contiguous range). */ - size = -mask_lo; - *base = base_hi << (32 - PAGE_SHIFT) | base_lo >> PAGE_SHIFT; - *end = *base + size - 1; -} - -bool_t is_var_mtrr_overlapped(struct mtrr_state *m) -{ - int32_t seg, i; - uint64_t phys_base, phys_mask, phys_base_pre, phys_mask_pre; - uint64_t base_pre, end_pre, base, end; - uint8_t num_var_ranges = (uint8_t)m->mtrr_cap; + unsigned int seg, i; + unsigned int num_var_ranges = (uint8_t)m->mtrr_cap; for ( i = 0; i < num_var_ranges; i++ ) { - phys_base_pre = ((uint64_t*)m->var_ranges)[i*2]; - phys_mask_pre = ((uint64_t*)m->var_ranges)[i*2 + 1]; + uint64_t base1 = m->var_ranges[i].base >> PAGE_SHIFT; + uint64_t mask1 = m->var_ranges[i].mask >> PAGE_SHIFT; - get_mtrr_range(phys_base_pre, phys_mask_pre, - &base_pre, &end_pre); + if ( !(m->var_ranges[i].mask & MTRR_PHYSMASK_VALID) ) + continue; for ( seg = i + 1; seg < num_var_ranges; seg ++ ) { - phys_base = ((uint64_t*)m->var_ranges)[seg*2]; - phys_mask = ((uint64_t*)m->var_ranges)[seg*2 + 1]; + uint64_t base2 = m->var_ranges[seg].base >> PAGE_SHIFT; + uint64_t mask2 = m->var_ranges[seg].mask >> PAGE_SHIFT; - get_mtrr_range(phys_base, phys_mask, - &base, &end); + if ( !(m->var_ranges[seg].mask & MTRR_PHYSMASK_VALID) ) + continue; - if ( ((base_pre != end_pre) && (base != end)) - || ((base >= base_pre) && (base <= end_pre)) - || ((end >= base_pre) && (end <= end_pre)) - || ((base_pre >= base) && (base_pre <= end)) - || ((end_pre >= base) && (end_pre <= end)) ) + if ( (base1 & mask1 & mask2) == (base2 & mask2 & mask1) ) { /* MTRR is overlapped. */ return 1; @@ -168,8 +133,6 @@ static int __init hvm_mtrr_pat_init(void } } - size_or_mask = ~((1 << (paddr_bits - PAGE_SHIFT)) - 1); - return 0; } __initcall(hvm_mtrr_pat_init); --- a/xen/include/asm-x86/mtrr.h +++ b/xen/include/asm-x86/mtrr.h @@ -91,7 +91,7 @@ extern bool_t mtrr_def_type_msr_set(stru extern void memory_type_changed(struct domain *); extern bool_t pat_msr_set(uint64_t *pat, uint64_t msr); -bool_t is_var_mtrr_overlapped(struct mtrr_state *m); +bool_t is_var_mtrr_overlapped(const struct mtrr_state *m); bool_t mtrr_pat_not_equal(struct vcpu *vd, struct vcpu *vs); #endif /* __ASM_X86_MTRR_H__ */