9ba0dde971
Avoids regressions where some code falsely think they cannot use some CPU features like AVX1, e.g., ZFS. Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
62 lines
2.4 KiB
Diff
62 lines
2.4 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Feng Tang <feng.tang@intel.com>
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Date: Wed, 23 Aug 2023 14:57:47 +0800
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Subject: [PATCH] x86/fpu: Set X86_FEATURE_OSXSAVE feature after enabling
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OSXSAVE in CR4
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0-Day found a 34.6% regression in stress-ng's 'af-alg' test case, and
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bisected it to commit b81fac906a8f ("x86/fpu: Move FPU initialization into
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arch_cpu_finalize_init()"), which optimizes the FPU init order, and moves
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the CR4_OSXSAVE enabling into a later place:
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arch_cpu_finalize_init
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identify_boot_cpu
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identify_cpu
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generic_identify
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get_cpu_cap --> setup cpu capability
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...
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fpu__init_cpu
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fpu__init_cpu_xstate
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cr4_set_bits(X86_CR4_OSXSAVE);
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As the FPU is not yet initialized the CPU capability setup fails to set
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X86_FEATURE_OSXSAVE. Many security module like 'camellia_aesni_avx_x86_64'
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depend on this feature and therefore fail to load, causing the regression.
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Cure this by setting X86_FEATURE_OSXSAVE feature right after OSXSAVE
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enabling.
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[ tglx: Moved it into the actual BSP FPU initialization code and added a comment ]
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Fixes: b81fac906a8f ("x86/fpu: Move FPU initialization into arch_cpu_finalize_init()")
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Reported-by: kernel test robot <oliver.sang@intel.com>
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Signed-off-by: Feng Tang <feng.tang@intel.com>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Cc: stable@vger.kernel.org
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Link: https://lore.kernel.org/lkml/202307192135.203ac24e-oliver.sang@intel.com
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Link: https://lore.kernel.org/lkml/20230823065747.92257-1-feng.tang@intel.com
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(cherry picked from commit 2c66ca3949dc701da7f4c9407f2140ae425683a5)
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Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
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---
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arch/x86/kernel/fpu/xstate.c | 7 +++++++
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1 file changed, 7 insertions(+)
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diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
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index 0bab497c9436..1afbc4866b10 100644
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--- a/arch/x86/kernel/fpu/xstate.c
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+++ b/arch/x86/kernel/fpu/xstate.c
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@@ -882,6 +882,13 @@ void __init fpu__init_system_xstate(unsigned int legacy_size)
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goto out_disable;
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}
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+ /*
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+ * CPU capabilities initialization runs before FPU init. So
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+ * X86_FEATURE_OSXSAVE is not set. Now that XSAVE is completely
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+ * functional, set the feature bit so depending code works.
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+ */
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+ setup_force_cpu_cap(X86_FEATURE_OSXSAVE);
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+
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print_xstate_offset_size();
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pr_info("x86/fpu: Enabled xstate features 0x%llx, context size is %d bytes, using '%s' format.\n",
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fpu_kernel_cfg.max_features,
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