linux-kernel - [RFC PATCH 2/8] x86/fpu/xstate: Fix guest fpstate allocation size calculation

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Message-Id: <20230914032334.75212-3-weijiang.yang@intel.com>
Date:   Wed, 13 Sep 2023 23:23:28 -0400
From:   Yang Weijiang <weijiang.yang@...el.com>
To:     x86@...nel.org, linux-kernel@...r.kernel.org
Cc:     dave.hansen@...el.com, tglx@...utronix.de, peterz@...radead.org,
        seanjc@...gle.com, pbonzini@...hat.com, rick.p.edgecombe@...el.com,
        kvm@...r.kernel.org, yang.zhong@...el.com, jing2.liu@...el.com,
        chao.gao@...el.com, Yang Weijiang <weijiang.yang@...el.com>
Subject: [RFC PATCH 2/8] x86/fpu/xstate: Fix guest fpstate allocation size calculation

Fix guest xsave area allocation size from fpu_user_cfg.default_size to
fpu_kernel_cfg.default_size so that the xsave area size is consistent
with fpstate->size set in __fpstate_reset().

With the fix, guest fpstate size is sufficient for KVM supported guest
xfeatures.

Fixes: 69f6ed1d14c6 ("x86/fpu: Provide infrastructure for KVM FPU cleanup");
Cc: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Yang Weijiang <weijiang.yang@...el.com>
---
 arch/x86/kernel/fpu/core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index a86d37052a64..a42d8ad26ce6 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -220,7 +220,9 @@ bool fpu_alloc_guest_fpstate(struct fpu_guest *gfpu)
 	struct fpstate *fpstate;
 	unsigned int size;
 
-	size = fpu_user_cfg.default_size + ALIGN(offsetof(struct fpstate, regs), 64);
+	size = fpu_kernel_cfg.default_size +
+	       ALIGN(offsetof(struct fpstate, regs), 64);
+
 	fpstate = vzalloc(size);
 	if (!fpstate)
 		return false;
-- 
2.27.0