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Message-Id: <20211217153003.1719189-3-jing2.liu@intel.com>
Date: Fri, 17 Dec 2021 07:29:42 -0800
From: Jing Liu <jing2.liu@...el.com>
To: x86@...nel.org, kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
dave.hansen@...ux.intel.com, pbonzini@...hat.com
Cc: seanjc@...gle.com, jun.nakajima@...el.com, kevin.tian@...el.com,
jing2.liu@...ux.intel.com, jing2.liu@...el.com,
guang.zeng@...el.com, wei.w.wang@...el.com, yang.zhong@...el.com
Subject: [PATCH v2 02/23] x86/fpu: Prepare guest FPU for dynamically enabled FPU features
From: Thomas Gleixner <tglx@...utronix.de>
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@...utronix.de>
Signed-off-by: Jing Liu <jing2.liu@...el.com>
---
arch/x86/include/asm/fpu/types.h | 13 +++++++++++++
arch/x86/kernel/fpu/core.c | 26 +++++++++++++++++++++++++-
2 files changed, 38 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h
index 6ddf80637697..c752d0aa23a4 100644
--- a/arch/x86/include/asm/fpu/types.h
+++ b/arch/x86/include/asm/fpu/types.h
@@ -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
*/
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index ab19b3d8b2f7..eddeeb4ed2f5 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -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(¤t->sighand->siglock);
+ fpuperm = ¤t->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(¤t->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);
--
2.27.0
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