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x86/fpu: Drop @perm from guest pseudo FPU container

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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@redhat.com>
Signed-off-by: Chao Gao <chao.gao@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Chang S. Bae <chang.seok.bae@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mitchell Levy <levymitchell0@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Samuel Holland <samuel.holland@sifive.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/kvm/af972fe5981b9e7101b64de43c7be0a8cc165323.camel@redhat.com/
Link: https://lore.kernel.org/r/20250506093740.2864458-3-chao.gao@intel.com
This commit is contained in:
Chao Gao
2025-05-06 17:36:07 +08:00
committed by Ingo Molnar
parent d8414603b2
commit 32d5fa804d
2 changed files with 2 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files

7
arch/x86/include/asm/fpu/types.h
View File

@@ -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.
*/

7
arch/x86/kernel/fpu/core.c
View File

@@ -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(&current->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;
}