5.15-stable patches

added patches:
	kvm-arm64-pkvm-fixup-boot-mode-to-reflect-that-the-kernel-resumes-from-el1.patch

diff --git a/queue-5.15/kvm-arm64-pkvm-fixup-boot-mode-to-reflect-that-the-kernel-resumes-from-el1.patch b/queue-5.15/kvm-arm64-pkvm-fixup-boot-mode-to-reflect-that-the-kernel-resumes-from-el1.patch
new file mode 100644 (file)
index 0000000..8f77e13
--- /dev/null
+++ b/queue-5.15/kvm-arm64-pkvm-fixup-boot-mode-to-reflect-that-the-kernel-resumes-from-el1.patch
@@ -0,0 +1,74 @@
+From vdonnefort@google.com  Tue Nov 29 17:52:03 2022
+From: Vincent Donnefort <vdonnefort@google.com>
+Date: Mon, 28 Nov 2022 18:52:22 +0000
+Subject: KVM: arm64: pkvm: Fixup boot mode to reflect that the kernel resumes from EL1
+To: gregkh@kernel.org
+Cc: kernel-team@android.com, Marc Zyngier <maz@kernel.org>, stable@vger.kernel.org,  Vincent Donnefort <vdonnefort@google.com>
+Message-ID: <20221128185222.1291038-1-vdonnefort@google.com>
+
+From: Marc Zyngier <maz@kernel.org>
+
+The kernel has an awfully complicated boot sequence in order to cope
+with the various EL2 configurations, including those that "enhanced"
+the architecture. We go from EL2 to EL1, then back to EL2, staying
+at EL2 if VHE capable and otherwise go back to EL1.
+
+Here's a paracetamol tablet for you.
+
+The cpu_resume path follows the same logic, because coming up with
+two versions of a square wheel is hard.
+
+However, things aren't this straightforward with pKVM, as the host
+resume path is always proxied by the hypervisor, which means that
+the kernel is always entered at EL1. Which contradicts what the
+__boot_cpu_mode[] array contains (it obviously says EL2).
+
+This thus triggers a HVC call from EL1 to EL2 in a vain attempt
+to upgrade from EL1 to EL2 VHE, which we are, funnily enough,
+reluctant to grant to the host kernel. This is also completely
+unexpected, and puzzles your average EL2 hacker.
+
+Address it by fixing up the boot mode at the point the host gets
+deprivileged. is_hyp_mode_available() and co already have a static
+branch to deal with this, making it pretty safe.
+
+This stable fix doesn't have an upstream version. The entire bootflow
+has been reworked from 6.0 and that fixed the boot mode at the same
+time, from commit 005e12676af0 ("arm64: head: record CPU boot mode after
+enabling the MMU") to be precise. However, the latter is part of a 20
+patches long series and can't be simply cherry-pick'ed.
+
+Link: https://lore.kernel.org/r/20220624150651.1358849-1-ardb@kernel.org/
+Link: https://lore.kernel.org/r/20221011165400.1241729-1-maz@kernel.org/
+Cc: <stable@vger.kernel.org> # 5.15+
+Reported-by: Vincent Donnefort <vdonnefort@google.com>
+Signed-off-by: Marc Zyngier <maz@kernel.org>
+Tested-by: Vincent Donnefort <vdonnefort@google.com>
+[Vincent: Add a paragraph about why this patch is for stable only]
+Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ arch/arm64/kvm/arm.c |   11 +++++++++++
+ 1 file changed, 11 insertions(+)
+
+--- a/arch/arm64/kvm/arm.c
++++ b/arch/arm64/kvm/arm.c
+@@ -2000,6 +2000,17 @@ static int pkvm_drop_host_privileges(voi
+        * once the host stage 2 is installed.
+        */
+       static_branch_enable(&kvm_protected_mode_initialized);
++
++      /*
++       * Fixup the boot mode so that we don't take spurious round
++       * trips via EL2 on cpu_resume. Flush to the PoC for a good
++       * measure, so that it can be observed by a CPU coming out of
++       * suspend with the MMU off.
++       */
++      __boot_cpu_mode[0] = __boot_cpu_mode[1] = BOOT_CPU_MODE_EL1;
++      dcache_clean_poc((unsigned long)__boot_cpu_mode,
++                       (unsigned long)(__boot_cpu_mode + 2));
++
+       on_each_cpu(_kvm_host_prot_finalize, &ret, 1);
+       return ret;
+ }

diff --git a/queue-5.15/series b/queue-5.15/series
index 777157ade56aed329c0a26bf3744023a70758f1d..96b20ff556aaf382bc6a52587be8587a1756c347 100644 (file)
--- a/queue-5.15/series
+++ b/queue-5.15/series
@@ -137,3 +137,4 @@ nios2-add-force-for-vmlinuz.gz.patch
 mmc-sdhci-brcmstb-re-organize-flags.patch
 mmc-sdhci-brcmstb-enable-clock-gating-to-save-power.patch
 mmc-sdhci-brcmstb-fix-sdhci_reset_all-for-cqhci.patch
+kvm-arm64-pkvm-fixup-boot-mode-to-reflect-that-the-kernel-resumes-from-el1.patch