Messages in this thread | | | Date | Fri, 21 Oct 2022 20:05:39 +0200 | Subject | Re: [PATCH v4 03/16] x86/mtrr: replace use_intel() with a local flag | From | Juergen Gross <> |
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On 21.10.22 19:19, Borislav Petkov wrote: > On Tue, Oct 04, 2022 at 10:10:10AM +0200, Juergen Gross wrote: >> In MTRR code use_intel() is only used in one source file, and the >> relevant use_intel_if member of struct mtrr_ops is set only in >> generic_mtrr_ops. >> >> Replace use_intel() with a single flag in cacheinfo.c, which can be set >> when assigning generic_mtrr_ops to mtrr_if. This allows to drop >> use_intel_if from mtrr_ops, while preparing to support PAT without >> MTRR. As another preparation for the PAT/MTRR decoupling use a bit for >> MTRR control and one for PAT control. For now set both bits together, >> this can be changed later. >> >> As the new flag will be set only if mtrr_enabled is set, the test for >> mtrr_enabled can be dropped at some places. >> >> At the same time drop the local mtrr_enabled() function and rename >> the __mtrr_enabled flag to mtrr_enabled. > > So, I kinda like your idea about "replace the bool with mtrr_if != NULL" > to test whether MTRRs are enabled. > > IOW, how does this look ontop of yours? > > At the end of mtrr_bp_init() I need to do some careful dancing but I > think this way it is even clearer. I'm pretty sure it can be simplified > even more but one thing at a time...
Please have a look at patch 10 (I've put it after the rework of mtrr_bp_init() exactly in order to avoid the dance you had to do).
Juergen
> > Thx. > > --- > diff --git a/arch/x86/kernel/cpu/mtrr/mtrr.c b/arch/x86/kernel/cpu/mtrr/mtrr.c > index dacb537da126..927b463a22bd 100644 > --- a/arch/x86/kernel/cpu/mtrr/mtrr.c > +++ b/arch/x86/kernel/cpu/mtrr/mtrr.c > @@ -59,7 +59,6 @@ > #define MTRR_TO_PHYS_WC_OFFSET 1000 > > u32 num_var_ranges; > -static bool mtrr_enabled; > > unsigned int mtrr_usage_table[MTRR_MAX_VAR_RANGES]; > static DEFINE_MUTEX(mtrr_mutex); > @@ -71,15 +70,17 @@ static const struct mtrr_ops *mtrr_ops[X86_VENDOR_NUM] __ro_after_init; > > const struct mtrr_ops *mtrr_if; > > -static void set_mtrr(unsigned int reg, unsigned long base, > - unsigned long size, mtrr_type type); > - > void __init set_mtrr_ops(const struct mtrr_ops *ops) > { > if (ops->vendor && ops->vendor < X86_VENDOR_NUM) > mtrr_ops[ops->vendor] = ops; > } > > +static bool mtrr_enabled(void) > +{ > + return !!mtrr_if; > +} > + > /* Returns non-zero if we have the write-combining memory type */ > static int have_wrcomb(void) > { > @@ -299,7 +300,7 @@ int mtrr_add_page(unsigned long base, unsigned long size, > int i, replace, error; > mtrr_type ltype; > > - if (!mtrr_enabled) > + if (!mtrr_enabled()) > return -ENXIO; > > error = mtrr_if->validate_add_page(base, size, type); > @@ -447,7 +448,7 @@ static int mtrr_check(unsigned long base, unsigned long size) > int mtrr_add(unsigned long base, unsigned long size, unsigned int type, > bool increment) > { > - if (!mtrr_enabled) > + if (!mtrr_enabled()) > return -ENODEV; > if (mtrr_check(base, size)) > return -EINVAL; > @@ -476,7 +477,7 @@ int mtrr_del_page(int reg, unsigned long base, unsigned long size) > unsigned long lbase, lsize; > int error = -EINVAL; > > - if (!mtrr_enabled) > + if (!mtrr_enabled()) > return -ENODEV; > > max = num_var_ranges; > @@ -536,7 +537,7 @@ int mtrr_del_page(int reg, unsigned long base, unsigned long size) > */ > int mtrr_del(int reg, unsigned long base, unsigned long size) > { > - if (!mtrr_enabled) > + if (!mtrr_enabled()) > return -ENODEV; > if (mtrr_check(base, size)) > return -EINVAL; > @@ -562,7 +563,7 @@ int arch_phys_wc_add(unsigned long base, unsigned long size) > { > int ret; > > - if (pat_enabled() || !mtrr_enabled) > + if (pat_enabled() || !mtrr_enabled()) > return 0; /* Success! (We don't need to do anything.) */ > > ret = mtrr_add(base, size, MTRR_TYPE_WRCOMB, true); > @@ -750,15 +751,18 @@ void __init mtrr_bp_init(void) > } > } > > - if (mtrr_if) { > - mtrr_enabled = true; > - set_num_var_ranges(mtrr_if == &generic_mtrr_ops); > + if (mtrr_enabled()) { > + bool use_generic = mtrr_if == &generic_mtrr_ops; > + bool mtrr_state_enabled = true; > + > + set_num_var_ranges(use_generic); > init_table(); > - if (mtrr_if == &generic_mtrr_ops) { > + > + if (use_generic) { > /* BIOS may override */ > - mtrr_enabled = get_mtrr_state(); > + mtrr_state_enabled = get_mtrr_state(); > > - if (mtrr_enabled) { > + if (mtrr_state_enabled) { > mtrr_bp_pat_init(); > memory_caching_control |= CACHE_MTRR | CACHE_PAT; > } > @@ -767,10 +771,13 @@ void __init mtrr_bp_init(void) > changed_by_mtrr_cleanup = 1; > mtrr_if->set_all(); > } > + > + if (!mtrr_state_enabled) > + mtrr_if = NULL; > } > } > > - if (!mtrr_enabled) { > + if (!mtrr_enabled()) { > pr_info("Disabled\n"); > > /* > @@ -811,7 +818,7 @@ void mtrr_save_state(void) > { > int first_cpu; > > - if (!mtrr_enabled) > + if (!mtrr_enabled()) > return; > > first_cpu = cpumask_first(cpu_online_mask); > @@ -856,7 +863,7 @@ void mtrr_bp_restore(void) > > static int __init mtrr_init_finialize(void) > { > - if (!mtrr_enabled) > + if (!mtrr_enabled()) > return 0; > > if (memory_caching_control & CACHE_MTRR) { >
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