From: Borislav Petkov <bp@alien8.de>
To: Juergen Gross <jgross@suse.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH v4 02/12] x86/mtrr: optimize mtrr_calc_physbits()
Date: Mon, 20 Mar 2023 13:50:38 +0100 [thread overview]
Message-ID: <20230320125038.GEZBhWnkON79eAbS04@fat_crate.local> (raw)
In-Reply-To: <20230306163425.8324-3-jgross@suse.com>
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.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2023-03-20 12:52 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-06 16:34 [PATCH v4 00/12] x86/mtrr: fix handling with PAT but without MTRR Juergen Gross
2023-03-06 16:34 ` [PATCH v4 01/12] x86/mtrr: split off physical address size calculation Juergen Gross
2023-03-06 16:34 ` [PATCH v4 02/12] x86/mtrr: optimize mtrr_calc_physbits() Juergen Gross
2023-03-20 12:50 ` Borislav Petkov [this message]
2023-03-06 16:34 ` [PATCH v4 03/12] x86/mtrr: support setting MTRR state for software defined MTRRs Juergen Gross
2023-03-20 12:59 ` Huang, Kai
2023-03-20 13:47 ` Juergen Gross
2023-03-20 21:34 ` Huang, Kai
2023-03-20 22:42 ` Borislav Petkov
2023-03-21 6:01 ` Juergen Gross
2023-03-20 19:05 ` Borislav Petkov
2023-03-21 6:00 ` Juergen Gross
2023-03-21 10:30 ` Borislav Petkov
2023-03-21 15:49 ` Juergen Gross
2023-03-06 16:34 ` [PATCH v4 04/12] x86/hyperv: set MTRR state when running as SEV-SNP Hyper-V guest Juergen Gross
2023-03-06 16:34 ` [PATCH v4 05/12] x86/xen: set MTRR state when running as Xen PV initial domain Juergen Gross
2023-03-07 21:47 ` Boris Ostrovsky
2023-03-23 12:43 ` Borislav Petkov
2023-03-06 16:34 ` [PATCH v4 06/12] x86/mtrr: replace vendor tests in MTRR code Juergen Gross
2023-03-24 16:56 ` Borislav Petkov
2023-03-27 5:43 ` Juergen Gross
2023-03-27 7:14 ` Borislav Petkov
2023-03-06 16:34 ` [PATCH v4 07/12] x86/mtrr: allocate mtrr_value array dynamically Juergen Gross
2023-03-20 12:25 ` Huang, Kai
2023-03-20 13:49 ` Juergen Gross
2023-03-20 15:31 ` Dave Hansen
2023-03-20 15:49 ` Juergen Gross
2023-03-26 22:05 ` Borislav Petkov
2023-03-27 5:44 ` Juergen Gross
2023-03-06 16:34 ` [PATCH v4 08/12] x86/mtrr: add get_effective_type() service function Juergen Gross
2023-03-06 16:34 ` [PATCH v4 09/12] x86/mtrr: construct a memory map with cache modes Juergen Gross
2023-03-29 12:51 ` Borislav Petkov
2023-03-29 13:39 ` Juergen Gross
2023-03-31 12:55 ` Borislav Petkov
2023-03-31 13:23 ` Juergen Gross
2023-04-01 14:24 ` Borislav Petkov
2023-04-03 6:57 ` Juergen Gross
2023-03-31 12:57 ` Borislav Petkov
2023-03-31 13:35 ` Juergen Gross
2023-04-01 14:26 ` Borislav Petkov
2023-04-03 7:02 ` Juergen Gross
2023-03-06 16:34 ` [PATCH v4 10/12] x86/mtrr: use new cache_map in mtrr_type_lookup() Juergen Gross
2023-03-06 16:34 ` [PATCH v4 11/12] x86/mtrr: don't let mtrr_type_lookup() return MTRR_TYPE_INVALID Juergen Gross
2023-03-06 16:34 ` [PATCH v4 12/12] x86/mm: only check uniform after calling mtrr_type_lookup() Juergen Gross
2023-03-07 21:09 ` [PATCH v4 00/12] x86/mtrr: fix handling with PAT but without MTRR Michael Kelley (LINUX)
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