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

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);