sys-kernel/linux-{image,sources}-redcore-lts-legacy : revision bump, revert https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/patch/?id=52918ed5fcf05d97d257f4131e19479da18f5d16, breaks kvm_amd

1 files changed, 91 insertions, 0 deletions

diff --git a/sys-kernel/linux-image-redcore-lts-legacy/files/4.19-revert_52918ed5fcf05d97d257f4131e19479da18f5d16.patch b/sys-kernel/linux-image-redcore-lts-legacy/files/4.19-revert_52918ed5fcf05d97d257f4131e19479da18f5d16.patch
new file mode 100644
index 00000000..d64d8efb
--- /dev/null
+++ b/sys-kernel/linux-image-redcore-lts-legacy/files/4.19-revert_52918ed5fcf05d97d257f4131e19479da18f5d16.patch
@@ -0,0 +1,91 @@
+From a4e761c9f63ae12c5e2fc586b77082fd07e54212 Mon Sep 17 00:00:00 2001
+From: Tom Lendacky <thomas.lendacky@amd.com>
+Date: Thu, 9 Jan 2020 17:42:16 -0600
+Subject: KVM: SVM: Override default MMIO mask if memory encryption is enabled
+
+commit 52918ed5fcf05d97d257f4131e19479da18f5d16 upstream.
+
+The KVM MMIO support uses bit 51 as the reserved bit to cause nested page
+faults when a guest performs MMIO. The AMD memory encryption support uses
+a CPUID function to define the encryption bit position. Given this, it is
+possible that these bits can conflict.
+
+Use svm_hardware_setup() to override the MMIO mask if memory encryption
+support is enabled. Various checks are performed to ensure that the mask
+is properly defined and rsvd_bits() is used to generate the new mask (as
+was done prior to the change that necessitated this patch).
+
+Fixes: 28a1f3ac1d0c ("kvm: x86: Set highest physical address bits in non-present/reserved SPTEs")
+Suggested-by: Sean Christopherson <sean.j.christopherson@intel.com>
+Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
+Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
+Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ arch/x86/kvm/svm.c | 43 +++++++++++++++++++++++++++++++++++++++++++
+ 1 file changed, 43 insertions(+)
+
+diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
+index 0219693bf08e..3f0565e1a7a8 100644
+--- a/arch/x86/kvm/svm.c
++++ b/arch/x86/kvm/svm.c
+@@ -1298,6 +1298,47 @@ static void shrink_ple_window(struct kvm_vcpu *vcpu)
+ 				    control->pause_filter_count, old);
+ }
+ 
++/*
++ * The default MMIO mask is a single bit (excluding the present bit),
++ * which could conflict with the memory encryption bit. Check for
++ * memory encryption support and override the default MMIO mask if
++ * memory encryption is enabled.
++ */
++static __init void svm_adjust_mmio_mask(void)
++{
++	unsigned int enc_bit, mask_bit;
++	u64 msr, mask;
++
++	/* If there is no memory encryption support, use existing mask */
++	if (cpuid_eax(0x80000000) < 0x8000001f)
++		return;
++
++	/* If memory encryption is not enabled, use existing mask */
++	rdmsrl(MSR_K8_SYSCFG, msr);
++	if (!(msr & MSR_K8_SYSCFG_MEM_ENCRYPT))
++		return;
++
++	enc_bit = cpuid_ebx(0x8000001f) & 0x3f;
++	mask_bit = boot_cpu_data.x86_phys_bits;
++
++	/* Increment the mask bit if it is the same as the encryption bit */
++	if (enc_bit == mask_bit)
++		mask_bit++;
++
++	/*
++	 * If the mask bit location is below 52, then some bits above the
++	 * physical addressing limit will always be reserved, so use the
++	 * rsvd_bits() function to generate the mask. This mask, along with
++	 * the present bit, will be used to generate a page fault with
++	 * PFER.RSV = 1.
++	 *
++	 * If the mask bit location is 52 (or above), then clear the mask.
++	 */
++	mask = (mask_bit < 52) ? rsvd_bits(mask_bit, 51) | PT_PRESENT_MASK : 0;
++
++	kvm_mmu_set_mmio_spte_mask(mask, PT_WRITABLE_MASK | PT_USER_MASK);
++}
++
+ static __init int svm_hardware_setup(void)
+ {
+ 	int cpu;
+@@ -1352,6 +1393,8 @@ static __init int svm_hardware_setup(void)
+ 		}
+ 	}
+ 
++	svm_adjust_mmio_mask();
++
+ 	for_each_possible_cpu(cpu) {
+ 		r = svm_cpu_init(cpu);
+ 		if (r)
+-- 
+cgit 1.2-0.3.lf.el7
+