Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | Date | Mon, 20 Mar 2023 13:50:38 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH v4 02/12] x86/mtrr: optimize mtrr_calc_physbits() |
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On Mon, Mar 06, 2023 at 05:34:15PM +0100, Juergen Gross wrote: > Optimize mtrr_calc_physbits() for better readability. > > Drop a stale comment, as reality has made it obsolete. > > Signed-off-by: Juergen Gross <jgross@suse.com> > --- > V3: > - new patch, split off from previous patch (Boris Petkov) > --- > arch/x86/kernel/cpu/mtrr/mtrr.c | 19 +++---------------- > 1 file changed, 3 insertions(+), 16 deletions(-)
Optimize some more:
--- From: Juergen Gross <jgross@suse.com> Date: Mon, 6 Mar 2023 17:34:15 +0100 Subject: [PATCH] x86/mtrr: Optimize mtrr_calc_physbits()
Optimize mtrr_calc_physbits() for better readability.
Drop a stale comment, as reality has made it obsolete.
[ bp: - s/mtrr/MTRR/ - s/boot_cpu_has/cpu_feature_enabled/ - use GENMASK_ULL - simplify. ]
Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20230306163425.8324-3-jgross@suse.com --- arch/x86/kernel/cpu/mtrr/mtrr.c | 27 +++++++-------------------- 1 file changed, 7 insertions(+), 20 deletions(-)
diff --git a/arch/x86/kernel/cpu/mtrr/mtrr.c b/arch/x86/kernel/cpu/mtrr/mtrr.c index 8310bdb111d0..deb22e989105 100644 --- a/arch/x86/kernel/cpu/mtrr/mtrr.c +++ b/arch/x86/kernel/cpu/mtrr/mtrr.c @@ -619,8 +619,6 @@ static struct syscore_ops mtrr_syscore_ops = { int __initdata changed_by_mtrr_cleanup; -#define SIZE_OR_MASK_BITS(n) (~((1ULL << ((n) - PAGE_SHIFT)) - 1)) - static unsigned int __init mtrr_calc_physbits(bool generic) { unsigned int phys_addr; @@ -628,15 +626,8 @@ static unsigned int __init mtrr_calc_physbits(bool generic) phys_addr = 32; if (generic) { - size_or_mask = SIZE_OR_MASK_BITS(36); - size_and_mask = 0x00f00000; phys_addr = 36; - /* - * This is an AMD specific MSR, but we assume(hope?) that - * Intel will implement it too when they extend the address - * bus of the Xeon. - */ if (cpuid_eax(0x80000000) >= 0x80000008) { phys_addr = cpuid_eax(0x80000008) & 0xff; /* CPUID workaround for Intel 0F33/0F34 CPU */ @@ -647,41 +638,37 @@ static unsigned int __init mtrr_calc_physbits(bool generic) boot_cpu_data.x86_stepping == 0x4)) phys_addr = 36; - size_or_mask = SIZE_OR_MASK_BITS(phys_addr); - size_and_mask = ~size_or_mask & 0xfffff00000ULL; } else if (boot_cpu_data.x86_vendor == X86_VENDOR_CENTAUR && boot_cpu_data.x86 == 6) { /* * VIA C* family have Intel style MTRRs, * but don't support PAE */ - size_or_mask = SIZE_OR_MASK_BITS(32); - size_and_mask = 0; phys_addr = 32; } - } else { - size_or_mask = SIZE_OR_MASK_BITS(32); - size_and_mask = 0; } + size_or_mask = ~GENMASK_ULL(phys_addr - PAGE_SHIFT, 0); + size_and_mask = ~size_or_mask & GENMASK_ULL(39, 20); + return phys_addr; } /** - * mtrr_bp_init - initialize mtrrs on the boot CPU + * mtrr_bp_init - initialize MTRRs on the boot CPU * * This needs to be called early; before any of the other CPUs are * initialized (i.e. before smp_init()). - * */ void __init mtrr_bp_init(void) { + bool generic_mtrrs = cpu_feature_enabled(X86_FEATURE_MTRR); const char *why = "(not available)"; unsigned int phys_addr; - phys_addr = mtrr_calc_physbits(boot_cpu_has(X86_FEATURE_MTRR)); + phys_addr = mtrr_calc_physbits(generic_mtrrs); - if (boot_cpu_has(X86_FEATURE_MTRR)) { + if (generic_mtrrs) { mtrr_if = &generic_mtrr_ops; } else { switch (boot_cpu_data.x86_vendor) { -- 2.35.1 -- Regards/Gruss, Boris.
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