[v2] KVM: arm64: Tidying up PAuth code in KVM

Commit Message

Fuad Tabba July 22, 2024, 4:33 p.m. UTC

Tidy up some of the PAuth trapping code to clear up some comments
and avoid clang/checkpatch warnings. Also, don't bother setting
PAuth HCR_EL2 bits in pKVM, since it's handled by the hypervisor.

Signed-off-by: Fuad Tabba <[e-mail]>
---
 arch/arm64/include/asm/kvm_ptrauth.h    |  2 +-
 arch/arm64/kvm/arm.c                    | 14 ++++----------
 arch/arm64/kvm/hyp/include/hyp/switch.h |  1 -
 arch/arm64/kvm/hyp/nvhe/switch.c        |  5 ++---
 4 files changed, 7 insertions(+), 15 deletions(-)


base-commit: 0c3836482481200ead7b416ca80c68a29cfdaabd

Comments

Oliver Upton Aug. 8, 2024, 5:08 p.m. UTC | #1

On Mon, 22 Jul 2024 17:33:11 +0100, Fuad Tabba wrote:
> Tidy up some of the PAuth trapping code to clear up some comments
> and avoid clang/checkpatch warnings. Also, don't bother setting
> PAuth HCR_EL2 bits in pKVM, since it's handled by the hypervisor.
> 
> 

Applied to kvmarm/fixes, thanks!

[1/1] KVM: arm64: Tidying up PAuth code in KVM
      https://git.kernel.org/kvmarm/kvmarm/c/7e814a20f6da

--
Best,
Oliver

Patch

diff --git a/arch/arm64/include/asm/kvm_ptrauth.h b/arch/arm64/include/asm/kvm_ptrauth.h
index d81bac256abc..6199c9f7ec6e 100644
--- a/arch/arm64/include/asm/kvm_ptrauth.h
+++ b/arch/arm64/include/asm/kvm_ptrauth.h
@@ -104,7 +104,7 @@  alternative_else_nop_endif
 
 #define __ptrauth_save_key(ctxt, key)					\
 	do {								\
-		u64 __val;                                              \
+		u64 __val;						\
 		__val = read_sysreg_s(SYS_ ## key ## KEYLO_EL1);	\
 		ctxt_sys_reg(ctxt, key ## KEYLO_EL1) = __val;		\
 		__val = read_sysreg_s(SYS_ ## key ## KEYHI_EL1);	\
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 59716789fe0f..95e6d22a9d3f 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -510,10 +510,10 @@  void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu)
 
 static void vcpu_set_pauth_traps(struct kvm_vcpu *vcpu)
 {
-	if (vcpu_has_ptrauth(vcpu)) {
+	if (vcpu_has_ptrauth(vcpu) && !is_protected_kvm_enabled()) {
 		/*
-		 * Either we're running running an L2 guest, and the API/APK
-		 * bits come from L1's HCR_EL2, or API/APK are both set.
+		 * Either we're running an L2 guest, and the API/APK bits come
+		 * from L1's HCR_EL2, or API/APK are both set.
 		 */
 		if (unlikely(vcpu_has_nv(vcpu) && !is_hyp_ctxt(vcpu))) {
 			u64 val;
@@ -530,16 +530,10 @@  static void vcpu_set_pauth_traps(struct kvm_vcpu *vcpu)
 		 * Save the host keys if there is any chance for the guest
 		 * to use pauth, as the entry code will reload the guest
 		 * keys in that case.
-		 * Protected mode is the exception to that rule, as the
-		 * entry into the EL2 code eagerly switch back and forth
-		 * between host and hyp keys (and kvm_hyp_ctxt is out of
-		 * reach anyway).
 		 */
-		if (is_protected_kvm_enabled())
-			return;
-
 		if (vcpu->arch.hcr_el2 & (HCR_API | HCR_APK)) {
 			struct kvm_cpu_context *ctxt;
+
 			ctxt = this_cpu_ptr_hyp_sym(kvm_hyp_ctxt);
 			ptrauth_save_keys(ctxt);
 		}
diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index 0c4de44534b7..9eb68c0dd727 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -27,7 +27,6 @@ 
 #include <asm/kvm_hyp.h>
 #include <asm/kvm_mmu.h>
 #include <asm/kvm_nested.h>
-#include <asm/kvm_ptrauth.h>
 #include <asm/fpsimd.h>
 #include <asm/debug-monitors.h>
 #include <asm/processor.h>
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index 6af179c6356d..8f5c56d5b1cd 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -173,9 +173,8 @@  static void __pmu_switch_to_host(struct kvm_vcpu *vcpu)
 static bool kvm_handle_pvm_sys64(struct kvm_vcpu *vcpu, u64 *exit_code)
 {
 	/*
-	 * Make sure we handle the exit for workarounds and ptrauth
-	 * before the pKVM handling, as the latter could decide to
-	 * UNDEF.
+	 * Make sure we handle the exit for workarounds before the pKVM
+	 * handling, as the latter could decide to UNDEF.
 	 */
 	return (kvm_hyp_handle_sysreg(vcpu, exit_code) ||
 		kvm_handle_pvm_sysreg(vcpu, exit_code));