Patch-mainline: v5.8-rc1
Git-commit: 25597f64c2f6fffa367d1e6ff4f62b9a751f9051
References: git-fixes
From: Vitaly Kuznetsov <vkuznets@redhat.com>
Date: Fri, 5 Jun 2020 13:59:06 +0200
Subject: [PATCH] Revert "KVM: x86: work around leak of uninitialized stack
 contents"

handle_vmptrst()/handle_vmread() stopped injecting #PF unconditionally
and switched to nested_vmx_handle_memory_failure() which just kills the
guest with KVM_EXIT_INTERNAL_ERROR in case of MMIO access, zeroing
'exception' in kvm_write_guest_virt_system() is not needed anymore.

This reverts commit 541ab2aeb28251bf7135c7961f3a6080eebcc705.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200605115906.532682-2-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
 arch/x86/kvm/x86.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 13512baf6f6e..c26dd1363151 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5647,13 +5647,6 @@ int kvm_write_guest_virt_system(struct kvm_vcpu *vcpu, gva_t addr, void *val,
 	/* kvm_write_guest_virt_system can pull in tons of pages. */
 	vcpu->arch.l1tf_flush_l1d = true;
 
-	/*
-	 * FIXME: this should call handle_emulation_failure if X86EMUL_IO_NEEDED
-	 * is returned, but our callers are not ready for that and they blindly
-	 * call kvm_inject_page_fault.  Ensure that they at least do not leak
-	 * uninitialized kernel stack memory into cr2 and error code.
-	 */
-	memset(exception, 0, sizeof(*exception));
 	return kvm_write_guest_virt_helper(addr, val, bytes, vcpu,
 					   PFERR_WRITE_MASK, exception);
 }
-- 
2.35.3