linux-kernel - [PATCH v7 2/6] x86/fpu: Add a pkru argument to copy_uabi_from_kernel_to

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Date:   Tue, 15 Nov 2022 15:09:28 -0800
From:   Kyle Huey <me@...ehuey.com>
To:     Dave Hansen <dave.hansen@...ux.intel.com>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>, Ingo Molnar <mingo@...hat.com>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Sean Christopherson <seanjc@...gle.com>,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
        Robert O'Callahan <robert@...llahan.org>,
        David Manouchehri <david.manouchehri@...eup.net>,
        Kyle Huey <me@...ehuey.com>
Subject: [PATCH v7 2/6] x86/fpu: Add a pkru argument to copy_uabi_from_kernel_to_xstate().

Both KVM (through KVM_SET_XSTATE) and ptrace (through PTRACE_SETREGSET
with NT_X86_XSTATE) ultimately call copy_uabi_from_kernel_to_xstate(),
but the canonical locations for the current PKRU value for KVM guests
and processes in a ptrace stop are different (in the kvm_vcpu_arch and
the thread_state structs respectively). In preparation for eventually
handling PKRU in copy_uabi_to_xstate, pass in a pointer to the PKRU
location.

Signed-off-by: Kyle Huey <me@...ehuey.com>
---
 arch/x86/kernel/fpu/core.c   | 2 +-
 arch/x86/kernel/fpu/regset.c | 2 +-
 arch/x86/kernel/fpu/xstate.c | 2 +-
 arch/x86/kernel/fpu/xstate.h | 2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 3b28c5b25e12..550157686323 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -406,7 +406,7 @@ int fpu_copy_uabi_to_guest_fpstate(struct fpu_guest *gfpu, const void *buf,
 	if (ustate->xsave.header.xfeatures & ~xcr0)
 		return -EINVAL;
 
-	ret = copy_uabi_from_kernel_to_xstate(kstate, ustate);
+	ret = copy_uabi_from_kernel_to_xstate(kstate, ustate, vpkru);
 	if (ret)
 		return ret;
 
diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c
index 75ffaef8c299..6d056b68f4ed 100644
--- a/arch/x86/kernel/fpu/regset.c
+++ b/arch/x86/kernel/fpu/regset.c
@@ -167,7 +167,7 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
 	}
 
 	fpu_force_restore(fpu);
-	ret = copy_uabi_from_kernel_to_xstate(fpu->fpstate, kbuf ?: tmpbuf);
+	ret = copy_uabi_from_kernel_to_xstate(fpu->fpstate, kbuf ?: tmpbuf, &target->thread.pkru);
 
 out:
 	vfree(tmpbuf);
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 32ba5d95628d..a4d24ae66796 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -1268,7 +1268,7 @@ static int copy_uabi_to_xstate(struct fpstate *fpstate, const void *kbuf,
  * Convert from a ptrace standard-format kernel buffer to kernel XSAVE[S]
  * format and copy to the target thread. Used by ptrace and KVM.
  */
-int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf)
+int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf, u32 *pkru)
 {
 	return copy_uabi_to_xstate(fpstate, kbuf, NULL);
 }
diff --git a/arch/x86/kernel/fpu/xstate.h b/arch/x86/kernel/fpu/xstate.h
index f08ee2722e74..a4ecb04d8d64 100644
--- a/arch/x86/kernel/fpu/xstate.h
+++ b/arch/x86/kernel/fpu/xstate.h
@@ -46,7 +46,7 @@ extern void __copy_xstate_to_uabi_buf(struct membuf to, struct fpstate *fpstate,
 				      u32 pkru_val, enum xstate_copy_mode copy_mode);
 extern void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk,
 				    enum xstate_copy_mode mode);
-extern int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf);
+extern int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf, u32 *pkru);
 extern int copy_sigframe_from_user_to_xstate(struct task_struct *tsk, const void __user *ubuf);
 
 
-- 
2.38.1