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x86/fpu: Prepare guest FPU for dynamically enabled FPU features

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To support dynamically enabled FPU features for guests prepare the guest
pseudo FPU container to keep track of the currently enabled xfeatures and
the guest permissions.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jing Liu <jing2.liu@intel.com>
Signed-off-by: Yang Zhong <yang.zhong@intel.com>
Message-Id: <20220105123532.12586-3-yang.zhong@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Thomas Gleixner 2022-01-05 04:35:13 -08:00 committed by Paolo Bonzini
parent 980fe2fddc
commit 36487e6228
2 changed files with 38 additions and 1 deletions
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13
arch/x86/include/asm/fpu/types.h
View file

@ -504,6 +504,19 @@ struct fpu {
* Guest pseudo FPU container
*/
struct fpu_guest {
/*
* @xfeatures: xfeature bitmap of features which are
* currently enabled for the guest vCPU.
*/
u64 xfeatures;
/*
* @perm: xfeature bitmap of features which are
* permitted to be enabled for the guest
* vCPU.
*/
u64 perm;
/*
* @fpstate: Pointer to the allocated guest fpstate
*/

26
arch/x86/kernel/fpu/core.c
View file

@ -201,6 +201,26 @@ void fpu_reset_from_exception_fixup(void)
#if IS_ENABLED(CONFIG_KVM)
static void __fpstate_reset(struct fpstate *fpstate);
static void fpu_init_guest_permissions(struct fpu_guest *gfpu)
{
struct fpu_state_perm *fpuperm;
u64 perm;
if (!IS_ENABLED(CONFIG_X86_64))
return;
spin_lock_irq(&current->sighand->siglock);
fpuperm = &current->group_leader->thread.fpu.guest_perm;
perm = fpuperm->__state_perm;
/* First fpstate allocation locks down permissions. */
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)
{
struct fpstate *fpstate;
@ -216,7 +236,11 @@ bool fpu_alloc_guest_fpstate(struct fpu_guest *gfpu)
fpstate->is_valloc = true;
fpstate->is_guest = true;
gfpu->fpstate = fpstate;
gfpu->fpstate = fpstate;
gfpu->xfeatures = fpu_user_cfg.default_features;
gfpu->perm = fpu_user_cfg.default_features;
fpu_init_guest_permissions(gfpu);
return true;
}
EXPORT_SYMBOL_GPL(fpu_alloc_guest_fpstate);