Subject: Patch "KVM: arm64: Set SCTLR_EL2.DSSBS if SSBD is forcefully disabled and !vhe" has been added to the 4.19-stable tree

From: <[email-masked]>
Date: Wed, 09 Oct 2019 10:04:02 +0200

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

    KVM: arm64: Set SCTLR_EL2.DSSBS if SSBD is forcefully disabled and !vhe

to the 4.19-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-set-sctlr_el2.dssbs-if-ssbd-is-forcefully-disabled-and-vhe.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <[email-masked]> know about it.

>From foo@baz Wed 09 Oct 2019 10:02:11 AM CEST
From: Ard Biesheuvel <[email-masked]>
Date: Tue,  8 Oct 2019 17:39:17 +0200
Subject: KVM: arm64: Set SCTLR_EL2.DSSBS if SSBD is forcefully disabled and !vhe
To: [email-masked]
Cc: [email-masked], Will Deacon <[email-masked]>, Christoffer Dall <[email-masked]>, Catalin Marinas <[email-masked]>, Ard Biesheuvel <[email-masked]>
Message-ID: <[email-masked]>

From: Will Deacon <[email-masked]>

[ Upstream commit 7c36447ae5a090729e7b129f24705bb231a07e0b ]

When running without VHE, it is necessary to set SCTLR_EL2.DSSBS if SSBD
has been forcefully disabled on the kernel command-line.

Acked-by: Christoffer Dall <[email-masked]>
Signed-off-by: Will Deacon <[email-masked]>
Signed-off-by: Catalin Marinas <[email-masked]>
Signed-off-by: Ard Biesheuvel <[email-masked]>
Signed-off-by: Greg Kroah-Hartman <[email-masked]>
---
 arch/arm64/include/asm/kvm_host.h |   11 +++++++++++
 arch/arm64/kvm/hyp/sysreg-sr.c    |   11 +++++++++++
 2 files changed, 22 insertions(+)

--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -398,6 +398,8 @@ struct kvm_vcpu *kvm_mpidr_to_vcpu(struc
 
 DECLARE_PER_CPU(kvm_cpu_context_t, kvm_host_cpu_state);
 
+void __kvm_enable_ssbs(void);
+
 static inline void __cpu_init_hyp_mode(phys_addr_t pgd_ptr,
 				       unsigned long hyp_stack_ptr,
 				       unsigned long vector_ptr)
@@ -418,6 +420,15 @@ static inline void __cpu_init_hyp_mode(p
 	 */
 	BUG_ON(!static_branch_likely(&arm64_const_caps_ready));
 	__kvm_call_hyp((void *)pgd_ptr, hyp_stack_ptr, vector_ptr, tpidr_el2);
+
+	/*
+	 * Disabling SSBD on a non-VHE system requires us to enable SSBS
+	 * at EL2.
+	 */
+	if (!has_vhe() && this_cpu_has_cap(ARM64_SSBS) &&
+	    arm64_get_ssbd_state() == ARM64_SSBD_FORCE_DISABLE) {
+		kvm_call_hyp(__kvm_enable_ssbs);
+	}
 }
 
 static inline bool kvm_arch_check_sve_has_vhe(void)
--- a/arch/arm64/kvm/hyp/sysreg-sr.c
+++ b/arch/arm64/kvm/hyp/sysreg-sr.c
@@ -293,3 +293,14 @@ void kvm_vcpu_put_sysregs(struct kvm_vcp
 
 	vcpu->arch.sysregs_loaded_on_cpu = false;
 }
+
+void __hyp_text __kvm_enable_ssbs(void)
+{
+	u64 tmp;
+
+	asm volatile(
+	"mrs	%0, sctlr_el2\n"
+	"orr	%0, %0, %1\n"
+	"msr	sctlr_el2, %0"
+	: "=&r" (tmp) : "L" (SCTLR_ELx_DSSBS));
+}

Patches currently in stable-queue which might be from [email-masked] are

queue-4.19/arm64-add-sysfs-vulnerability-show-for-meltdown.patch
queue-4.19/arm64-force-ssbs-on-context-switch.patch
queue-4.19/arm64-enable-generic-cpu-vulnerabilites-support.patch
queue-4.19/arm64-provide-a-command-line-to-disable-spectre_v2-mitigation.patch
queue-4.19/arm64-always-enable-spectre-v2-vulnerability-detection.patch
queue-4.19/arm64-docs-document-ssbs-hwcap.patch
queue-4.19/arm64-add-sysfs-vulnerability-show-for-spectre-v1.patch
queue-4.19/arm64-add-sysfs-vulnerability-show-for-speculative-store-bypass.patch
queue-4.19/kvm-arm64-set-sctlr_el2.dssbs-if-ssbd-is-forcefully-disabled-and-vhe.patch
queue-4.19/arm64-always-enable-ssb-vulnerability-detection.patch
queue-4.19/arm64-advertise-mitigation-of-spectre-v2-or-lack-thereof.patch
queue-4.19/arm64-ssbs-don-t-treat-cpus-with-ssbs-as-unaffected-by-ssb.patch
queue-4.19/crypto-skcipher-unmap-pages-after-an-external-error.patch
queue-4.19/arm64-cpufeature-detect-ssbs-and-advertise-to-userspace.patch
queue-4.19/arm64-ssbd-add-support-for-pstate.ssbs-rather-than-trapping-to-el3.patch
queue-4.19/arm64-fix-ssbs-sanitization.patch
queue-4.19/arm64-add-sysfs-vulnerability-show-for-spectre-v2.patch

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