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Date: Thu, 3 Nov 2022 14:24:56 +0100
From: Juergen Gross <jgross@...e.com>
To: Brian Gerst <brgerst@...il.com>
Cc: linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org,
x86@...nel.org, Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
"H. Peter Anvin" <hpa@...or.com>, Pu Wen <puwen@...on.cn>,
Andy Lutomirski <luto@...nel.org>,
Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH 4/4] x86: switch to cpu_feature_enabled() for
X86_FEATURE_XENPV
On 03.11.22 14:19, Brian Gerst wrote:
> On Thu, Nov 3, 2022 at 8:37 AM Juergen Gross <jgross@...e.com> wrote:
>>
>> Convert the remaining cases of static_cpu_has(X86_FEATURE_XENPV) and
>> boot_cpu_has(X86_FEATURE_XENPV) to use cpu_feature_enabled(), allowing
>> more efficient code in case the kernel is configured without
>> CONFIG_XEN_PV.
>>
>> Signed-off-by: Juergen Gross <jgross@...e.com>
>> ---
>> arch/x86/kernel/cpu/amd.c | 2 +-
>> arch/x86/kernel/cpu/bugs.c | 2 +-
>> arch/x86/kernel/cpu/hygon.c | 2 +-
>> arch/x86/kernel/process_64.c | 4 ++--
>> arch/x86/kernel/topology.c | 2 +-
>> arch/x86/mm/cpu_entry_area.c | 2 +-
>> 6 files changed, 7 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
>> index 860b60273df3..697fe881e967 100644
>> --- a/arch/x86/kernel/cpu/amd.c
>> +++ b/arch/x86/kernel/cpu/amd.c
>> @@ -985,7 +985,7 @@ static void init_amd(struct cpuinfo_x86 *c)
>> set_cpu_cap(c, X86_FEATURE_3DNOWPREFETCH);
>>
>> /* AMD CPUs don't reset SS attributes on SYSRET, Xen does. */
>> - if (!cpu_has(c, X86_FEATURE_XENPV))
>> + if (!cpu_feature_enabled(X86_FEATURE_XENPV))
>> set_cpu_bug(c, X86_BUG_SYSRET_SS_ATTRS);
>>
>> /*
>> diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
>> index da7c361f47e0..7f78e1527c5e 100644
>> --- a/arch/x86/kernel/cpu/bugs.c
>> +++ b/arch/x86/kernel/cpu/bugs.c
>> @@ -1302,7 +1302,7 @@ static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)
>> return SPECTRE_V2_CMD_AUTO;
>> }
>>
>> - if (cmd == SPECTRE_V2_CMD_IBRS && boot_cpu_has(X86_FEATURE_XENPV)) {
>> + if (cmd == SPECTRE_V2_CMD_IBRS && cpu_feature_enabled(X86_FEATURE_XENPV)) {
>> pr_err("%s selected but running as XenPV guest. Switching to AUTO select\n",
>> mitigation_options[i].option);
>> return SPECTRE_V2_CMD_AUTO;
>> diff --git a/arch/x86/kernel/cpu/hygon.c b/arch/x86/kernel/cpu/hygon.c
>> index 21fd425088fe..1c27645fd429 100644
>> --- a/arch/x86/kernel/cpu/hygon.c
>> +++ b/arch/x86/kernel/cpu/hygon.c
>> @@ -339,7 +339,7 @@ static void init_hygon(struct cpuinfo_x86 *c)
>> set_cpu_cap(c, X86_FEATURE_ARAT);
>>
>> /* Hygon CPUs don't reset SS attributes on SYSRET, Xen does. */
>> - if (!cpu_has(c, X86_FEATURE_XENPV))
>> + if (!cpu_feature_enabled(X86_FEATURE_XENPV))
>> set_cpu_bug(c, X86_BUG_SYSRET_SS_ATTRS);
>>
>> check_null_seg_clears_base(c);
>> diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
>> index 6b3418bff326..e2f469175be8 100644
>> --- a/arch/x86/kernel/process_64.c
>> +++ b/arch/x86/kernel/process_64.c
>> @@ -165,7 +165,7 @@ static noinstr unsigned long __rdgsbase_inactive(void)
>>
>> lockdep_assert_irqs_disabled();
>>
>> - if (!static_cpu_has(X86_FEATURE_XENPV)) {
>> + if (!cpu_feature_enabled(X86_FEATURE_XENPV)) {
>> native_swapgs();
>> gsbase = rdgsbase();
>> native_swapgs();
>> @@ -190,7 +190,7 @@ static noinstr void __wrgsbase_inactive(unsigned long gsbase)
>> {
>> lockdep_assert_irqs_disabled();
>>
>> - if (!static_cpu_has(X86_FEATURE_XENPV)) {
>> + if (!cpu_feature_enabled(X86_FEATURE_XENPV)) {
>> native_swapgs();
>> wrgsbase(gsbase);
>> native_swapgs();
>> diff --git a/arch/x86/kernel/topology.c b/arch/x86/kernel/topology.c
>> index 8617d1ed9d31..1b83377274b8 100644
>> --- a/arch/x86/kernel/topology.c
>> +++ b/arch/x86/kernel/topology.c
>> @@ -106,7 +106,7 @@ int arch_register_cpu(int num)
>> * Xen PV guests don't support CPU0 hotplug at all.
>> */
>> if (c->x86_vendor != X86_VENDOR_INTEL ||
>> - boot_cpu_has(X86_FEATURE_XENPV))
>> + cpu_feature_enabled(X86_FEATURE_XENPV))
>> cpu0_hotpluggable = 0;
>>
>> /*
>> diff --git a/arch/x86/mm/cpu_entry_area.c b/arch/x86/mm/cpu_entry_area.c
>> index 6c2f1b76a0b6..c83799753d44 100644
>> --- a/arch/x86/mm/cpu_entry_area.c
>> +++ b/arch/x86/mm/cpu_entry_area.c
>> @@ -147,7 +147,7 @@ static void __init setup_cpu_entry_area(unsigned int cpu)
>> * On Xen PV, the GDT must be read-only because the hypervisor
>> * requires it.
>> */
>> - pgprot_t gdt_prot = boot_cpu_has(X86_FEATURE_XENPV) ?
>> + pgprot_t gdt_prot = cpu_feature_enabled(X86_FEATURE_XENPV) ?
>> PAGE_KERNEL_RO : PAGE_KERNEL;
>> pgprot_t tss_prot = PAGE_KERNEL;
>> #endif
>
> This is another case that can be removed because it's for 32-bit.
Oh yes, indeed. Thanks for noticing.
Juergen
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