FAILED: patch "[PATCH] KVM: x86: Re-pend GET_NESTED_STATE_PAGES if getting said" failed to apply to 6.1-stable tree

FAILED: patch "[PATCH] KVM: x86: Re-pend GET_NESTED_STATE_PAGES if getting said" failed to apply to 6.1-stable tree

[gregkh]

The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 10180a277549339020b08000206092c07e0bff5a
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026092946-laxative-rival-2080@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 10180a277549339020b08000206092c07e0bff5a Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@google.com>
Date: Mon, 21 Sep 2026 14:16:07 -0700
Subject: [PATCH] KVM: x86: Re-pend GET_NESTED_STATE_PAGES if getting said
 pages fails

Re-pend GET_NESTED_STATE_PAGES before exiting to userspace if getting the
nested pages fails in the KVM_RUN path.  If userspace re-runs the vCPU, and
vmcs02 holds valid PFNs from the *previous* run of L2, then KVM could
re-enter L2 with stale, unpinned PFNs mapped into e.g. the vAPIC page.

Note, both SVM and VMX (as of commit 11722439fb20 ("KVM: nVMX: Ensure
KVM_REQ_GET_NESTED_STATE_PAGES is cleared on VM-Exit") ensure the request
is cleared on VM-Exit (including the "forced" case), i.e. there is no risk
of double-mapping due to emulated VMLAUNCH/VMRESUME/VMRUN *and* the request
trying to map the nested pages.

Fixes: 671ddc700fd0 ("KVM: nVMX: Don't leak L1 MMIO regions to L2")
Cc: stable@vger.kernel.org
Reported-by: Jinwoo Lee <rkskek9254@gmail.com>
Closes: https://lore.kernel.org/all/20260813043932.3214460-1-rkskek9254@gmail.com
Reported-by: Stefan Teodorescu <fane@google.com>
Link: https://patch.msgid.link/20260921211608.1030158-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a137dc6dd8c6..4ec17aaff413 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8072,6 +8072,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 
 		if (kvm_check_request(KVM_REQ_GET_NESTED_STATE_PAGES, vcpu)) {
 			if (unlikely(!kvm_nested_call(get_nested_state_pages)(vcpu))) {
+				kvm_make_request(KVM_REQ_GET_NESTED_STATE_PAGES, vcpu);
 				r = 0;
 				goto out;
 			}

[PATCH 6.1.y 1/2] KVM: x86: Reject nested CAP enablement if nested virtualization is disabled

[Sasha Levin]

From: Sean Christopherson <seanjc@google.com>

[ Upstream commit b65699be2c606d2687593516d93e66d16a713b61 ]

Add a flag to explicitly track if nested virtualization is enabled, and use
it enumerate that various nested CAPs are unsupported, and to reject
enablement of said CAPs.  When the nested ops hooks were moved to their
own structure, KVM's NULL-by-default behavior was deliberately dropped,
with the changelog asserting that all was well.  That wasn't quite true;
there is no danger to KVM, but now KVM is over-reporting support for
KVM_CAP_NESTED_STATE and KVM_CAP_HYPERV_ENLIGHTENED_VMCS.

Fixes: 33b22172452f ("KVM: x86: move nested-related kvm_x86_ops to a separate struct")
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://patch.msgid.link/20260630202828.440724-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Backport notes for 6.1:
Keep the capability handler's existing function-scope declarations and
add the nested-enabled check without importing the newer case-local block.

Provide kvm_nested_call() as a macro around the existing nested_ops
function pointer and use it for get_nested_state_pages().  Match the
upstream blank line before that request handler so commit
10180a277549339020b08000206092c07e0bff5a applies unchanged.  This preserves
the current dispatch behavior without importing the static-call conversion
or adding functions.  The request re-pending fix remains in the target.

Stable-dep-of: 10180a277549 ("KVM: x86: Re-pend GET_NESTED_STATE_PAGES if getting said pages fails")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/include/asm/kvm_host.h |  4 ++++
 arch/x86/kvm/hyperv.c           |  3 ++-
 arch/x86/kvm/svm/svm.c          |  1 +
 arch/x86/kvm/vmx/vmx.c          |  1 +
 arch/x86/kvm/x86.c              | 15 +++++++++------
 5 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 31395c43416dd..a4199606edfd0 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1643,6 +1643,8 @@ struct kvm_x86_ops {
 };
 
 struct kvm_x86_nested_ops {
+	bool enabled;
+
 	void (*leave_nested)(struct kvm_vcpu *vcpu);
 	bool (*is_exception_vmexit)(struct kvm_vcpu *vcpu, u8 vector,
 				    u32 error_code);
@@ -1693,6 +1695,8 @@ extern struct kvm_x86_ops kvm_x86_ops;
 #define KVM_X86_OP_OPTIONAL_RET0 KVM_X86_OP
 #include <asm/kvm-x86-ops.h>
 
+#define kvm_nested_call(func) (kvm_x86_ops.nested_ops->func)
+
 int kvm_x86_vendor_init(struct kvm_x86_init_ops *ops);
 void kvm_x86_vendor_exit(void);
 
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index bddeb5a28b23f..528da4e0f7e05 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -2457,7 +2457,8 @@ int kvm_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid,
 	};
 	int i, nent = ARRAY_SIZE(cpuid_entries);
 
-	if (kvm_x86_ops.nested_ops->get_evmcs_version)
+	if (kvm_x86_ops.nested_ops->enabled &&
+	    kvm_x86_ops.nested_ops->get_evmcs_version)
 		evmcs_ver = kvm_x86_ops.nested_ops->get_evmcs_version(vcpu);
 
 	if (cpuid->nent < nent)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 88979fefaa284..b3fb174e11523 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -5110,6 +5110,7 @@ static __init int svm_hardware_setup(void)
 		printk(KERN_INFO "kvm: Nested Virtualization enabled\n");
 		kvm_enable_efer_bits(EFER_SVME | EFER_LMSLE);
 	}
+	svm_nested_ops.enabled = nested;
 
 	/*
 	 * KVM's MMU doesn't support using 2-level paging for itself, and thus
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index cc10bde20d451..557b1ab8ea358 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -8549,6 +8549,7 @@ static __init int hardware_setup(void)
 		if (r)
 			return r;
 	}
+	vmx_nested_ops.enabled = nested;
 
 	vmx_set_cpu_caps();
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ffbf532baf7cd..d5686a1ee3287 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4516,14 +4516,15 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 		r = KVM_X2APIC_API_VALID_FLAGS;
 		break;
 	case KVM_CAP_NESTED_STATE:
-		r = kvm_x86_ops.nested_ops->get_state ?
+		r = kvm_x86_ops.nested_ops->enabled ?
 			kvm_x86_ops.nested_ops->get_state(NULL, NULL, 0) : 0;
 		break;
 	case KVM_CAP_HYPERV_DIRECT_TLBFLUSH:
 		r = kvm_x86_ops.enable_direct_tlbflush != NULL;
 		break;
 	case KVM_CAP_HYPERV_ENLIGHTENED_VMCS:
-		r = kvm_x86_ops.nested_ops->enable_evmcs != NULL;
+		r = kvm_x86_ops.nested_ops->enabled &&
+		    kvm_x86_ops.nested_ops->enable_evmcs != NULL;
 		break;
 	case KVM_CAP_SMALLER_MAXPHYADDR:
 		r = (int) allow_smaller_maxphyaddr;
@@ -5544,7 +5545,8 @@ static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,
 		return kvm_hv_activate_synic(vcpu, cap->cap ==
 					     KVM_CAP_HYPERV_SYNIC2);
 	case KVM_CAP_HYPERV_ENLIGHTENED_VMCS:
-		if (!kvm_x86_ops.nested_ops->enable_evmcs)
+		if (!kvm_x86_ops.nested_ops->enabled ||
+		    !kvm_x86_ops.nested_ops->enable_evmcs)
 			return -ENOTTY;
 		r = kvm_x86_ops.nested_ops->enable_evmcs(vcpu, &vmcs_version);
 		if (!r) {
@@ -5899,7 +5901,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 		u32 user_data_size;
 
 		r = -EINVAL;
-		if (!kvm_x86_ops.nested_ops->get_state)
+		if (!kvm_x86_ops.nested_ops->enabled)
 			break;
 
 		BUILD_BUG_ON(sizeof(user_data_size) != sizeof(user_kvm_nested_state->size));
@@ -5929,7 +5931,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 		int idx;
 
 		r = -EINVAL;
-		if (!kvm_x86_ops.nested_ops->set_state)
+		if (!kvm_x86_ops.nested_ops->enabled)
 			break;
 
 		r = -EFAULT;
@@ -10654,8 +10656,9 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 			r = -EIO;
 			goto out;
 		}
+
 		if (kvm_check_request(KVM_REQ_GET_NESTED_STATE_PAGES, vcpu)) {
-			if (unlikely(!kvm_x86_ops.nested_ops->get_nested_state_pages(vcpu))) {
+			if (unlikely(!kvm_nested_call(get_nested_state_pages)(vcpu))) {
 				r = 0;
 				goto out;
 			}
-- 
2.53.0

[PATCH 6.1.y 2/2] KVM: x86: Re-pend GET_NESTED_STATE_PAGES if getting said pages fails

[Sasha Levin]

From: Sean Christopherson <seanjc@google.com>

[ Upstream commit 10180a277549339020b08000206092c07e0bff5a ]

Re-pend GET_NESTED_STATE_PAGES before exiting to userspace if getting the
nested pages fails in the KVM_RUN path.  If userspace re-runs the vCPU, and
vmcs02 holds valid PFNs from the *previous* run of L2, then KVM could
re-enter L2 with stale, unpinned PFNs mapped into e.g. the vAPIC page.

Note, both SVM and VMX (as of commit 11722439fb20 ("KVM: nVMX: Ensure
KVM_REQ_GET_NESTED_STATE_PAGES is cleared on VM-Exit") ensure the request
is cleared on VM-Exit (including the "forced" case), i.e. there is no risk
of double-mapping due to emulated VMLAUNCH/VMRESUME/VMRUN *and* the request
trying to map the nested pages.

Fixes: 671ddc700fd0 ("KVM: nVMX: Don't leak L1 MMIO regions to L2")
Cc: stable@vger.kernel.org
Reported-by: Jinwoo Lee <rkskek9254@gmail.com>
Closes: https://lore.kernel.org/all/20260813043932.3214460-1-rkskek9254@gmail.com
Reported-by: Stefan Teodorescu <fane@google.com>
Link: https://patch.msgid.link/20260921211608.1030158-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/kvm/x86.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d5686a1ee3287..302328a64e273 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10659,6 +10659,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 
 		if (kvm_check_request(KVM_REQ_GET_NESTED_STATE_PAGES, vcpu)) {
 			if (unlikely(!kvm_nested_call(get_nested_state_pages)(vcpu))) {
+				kvm_make_request(KVM_REQ_GET_NESTED_STATE_PAGES, vcpu);
 				r = 0;
 				goto out;
 			}
-- 
2.53.0