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Message-ID: <20250506093740.2864458-3-chao.gao@intel.com>
Date: Tue, 6 May 2025 17:36:07 +0800
From: Chao Gao <chao.gao@...el.com>
To: x86@...nel.org,
linux-kernel@...r.kernel.org,
kvm@...r.kernel.org,
tglx@...utronix.de,
dave.hansen@...el.com,
seanjc@...gle.com,
pbonzini@...hat.com
Cc: peterz@...radead.org,
rick.p.edgecombe@...el.com,
weijiang.yang@...el.com,
john.allen@....com,
bp@...en8.de,
chang.seok.bae@...el.com,
xin3.li@...el.com,
Chao Gao <chao.gao@...el.com>,
Maxim Levitsky <mlevitsk@...hat.com>,
Ingo Molnar <mingo@...hat.com>,
Dave Hansen <dave.hansen@...ux.intel.com>,
"H. Peter Anvin" <hpa@...or.com>,
Mitchell Levy <levymitchell0@...il.com>,
Samuel Holland <samuel.holland@...ive.com>,
Kees Cook <kees@...nel.org>,
Oleg Nesterov <oleg@...hat.com>,
Eric Biggers <ebiggers@...gle.com>
Subject: [PATCH v6 2/7] x86/fpu: Drop @perm from guest pseudo FPU container
Remove @perm from the guest pseudo FPU container. The field is
initialized during allocation and never used later.
Rename fpu_init_guest_permissions() to show that its sole purpose is to
lock down guest permissions.
Suggested-by: Maxim Levitsky <mlevitsk@...hat.com>
Signed-off-by: Chao Gao <chao.gao@...el.com>
Reviewed-by: Chang S. Bae <chang.seok.bae@...el.com>
Link: https://lore.kernel.org/kvm/af972fe5981b9e7101b64de43c7be0a8cc165323.camel@redhat.com/
---
v6: add Chang's Reviewed-by
v5: drop the useless fpu_guest argument (Chang)
---
arch/x86/include/asm/fpu/types.h | 7 -------
arch/x86/kernel/fpu/core.c | 7 ++-----
2 files changed, 2 insertions(+), 12 deletions(-)
diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h
index e64db0eb9d27..1c94121acd3d 100644
--- a/arch/x86/include/asm/fpu/types.h
+++ b/arch/x86/include/asm/fpu/types.h
@@ -535,13 +535,6 @@ struct fpu_guest {
*/
u64 xfeatures;
- /*
- * @perm: xfeature bitmap of features which are
- * permitted to be enabled for the guest
- * vCPU.
- */
- u64 perm;
-
/*
* @xfd_err: Save the guest value.
*/
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 105b1b80d88d..1cda5b78540b 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -212,7 +212,7 @@ void fpu_reset_from_exception_fixup(void)
#if IS_ENABLED(CONFIG_KVM)
static void __fpstate_reset(struct fpstate *fpstate, u64 xfd);
-static void fpu_init_guest_permissions(struct fpu_guest *gfpu)
+static void fpu_lock_guest_permissions(void)
{
struct fpu_state_perm *fpuperm;
u64 perm;
@@ -228,8 +228,6 @@ static void fpu_init_guest_permissions(struct fpu_guest *gfpu)
WRITE_ONCE(fpuperm->__state_perm, perm | FPU_GUEST_PERM_LOCKED);
spin_unlock_irq(¤t->sighand->siglock);
-
- gfpu->perm = perm & ~FPU_GUEST_PERM_LOCKED;
}
bool fpu_alloc_guest_fpstate(struct fpu_guest *gfpu)
@@ -250,7 +248,6 @@ bool fpu_alloc_guest_fpstate(struct fpu_guest *gfpu)
gfpu->fpstate = fpstate;
gfpu->xfeatures = fpu_kernel_cfg.default_features;
- gfpu->perm = fpu_kernel_cfg.default_features;
/*
* KVM sets the FP+SSE bits in the XSAVE header when copying FPU state
@@ -265,7 +262,7 @@ bool fpu_alloc_guest_fpstate(struct fpu_guest *gfpu)
if (WARN_ON_ONCE(fpu_user_cfg.default_size > gfpu->uabi_size))
gfpu->uabi_size = fpu_user_cfg.default_size;
- fpu_init_guest_permissions(gfpu);
+ fpu_lock_guest_permissions();
return true;
}
--
2.47.1
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