Patch "KVM: arm64: Save PSTATE early on exit" has been added to the 5.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    KVM: arm64: Save PSTATE early on exit

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     kvm-arm64-save-pstate-early-on-exit.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 987d1110efad2a5bc969a59b3367899a19a6c2f5
Author: Marc Zyngier <maz@xxxxxxxxxx>
Date:   Tue Nov 16 10:20:06 2021 +0000

    KVM: arm64: Save PSTATE early on exit
    
    [ Upstream commit 83bb2c1a01d7127d5adc7d69d7aaa3f7072de2b4 ]
    
    In order to be able to use primitives such as vcpu_mode_is_32bit(),
    we need to synchronize the guest PSTATE. However, this is currently
    done deep into the bowels of the world-switch code, and we do have
    helpers evaluating this much earlier (__vgic_v3_perform_cpuif_access
    and handle_aarch32_guest, for example).
    
    Move the saving of the guest pstate into the early fixups, which
    cures the first issue. The second one will be addressed separately.
    
    Tested-by: Fuad Tabba <tabba@xxxxxxxxxx>
    Reviewed-by: Fuad Tabba <tabba@xxxxxxxxxx>
    Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index 1f875a8f20c47..8116ae1e636a2 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -406,6 +406,12 @@ static inline bool __hyp_handle_ptrauth(struct kvm_vcpu *vcpu)
  */
 static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
 {
+	/*
+	 * Save PSTATE early so that we can evaluate the vcpu mode
+	 * early on.
+	 */
+	vcpu->arch.ctxt.regs.pstate = read_sysreg_el2(SYS_SPSR);
+
 	if (ARM_EXCEPTION_CODE(*exit_code) != ARM_EXCEPTION_IRQ)
 		vcpu->arch.fault.esr_el2 = read_sysreg_el2(SYS_ESR);
 
diff --git a/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h
index cce43bfe158fa..0eacfb9d17b02 100644
--- a/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h
+++ b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h
@@ -54,7 +54,12 @@ static inline void __sysreg_save_el1_state(struct kvm_cpu_context *ctxt)
 static inline void __sysreg_save_el2_return_state(struct kvm_cpu_context *ctxt)
 {
 	ctxt->regs.pc			= read_sysreg_el2(SYS_ELR);
-	ctxt->regs.pstate		= read_sysreg_el2(SYS_SPSR);
+	/*
+	 * Guest PSTATE gets saved at guest fixup time in all
+	 * cases. We still need to handle the nVHE host side here.
+	 */
+	if (!has_vhe() && ctxt->__hyp_running_vcpu)
+		ctxt->regs.pstate	= read_sysreg_el2(SYS_SPSR);
 
 	if (cpus_have_final_cap(ARM64_HAS_RAS_EXTN))
 		ctxt_sys_reg(ctxt, DISR_EL1) = read_sysreg_s(SYS_VDISR_EL2);