linux-kernel - [PATCH AUTOSEL 5.10 02/15] KVM: arm64: Save PSTATE early on exit

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Message-Id: <20211206211520.1660478-2-sashal@kernel.org>
Date:   Mon,  6 Dec 2021 16:15:02 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Marc Zyngier <maz@...nel.org>, Fuad Tabba <tabba@...gle.com>,
        Sasha Levin <sashal@...nel.org>, catalin.marinas@....com,
        will@...nel.org, ardb@...nel.org, alexandru.elisei@....com,
        qperret@...gle.com, ascull@...gle.com, mark.rutland@....com,
        steven.price@....com, linux-arm-kernel@...ts.infradead.org,
        kvmarm@...ts.cs.columbia.edu
Subject: [PATCH AUTOSEL 5.10 02/15] KVM: arm64: Save PSTATE early on exit

From: Marc Zyngier <maz@...nel.org>

[ 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@...gle.com>
Reviewed-by: Fuad Tabba <tabba@...gle.com>
Signed-off-by: Marc Zyngier <maz@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/arm64/kvm/hyp/include/hyp/switch.h    | 6 ++++++
 arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h | 7 ++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

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);
-- 
2.33.0