FAILED: patch "[PATCH] KVM: x86/mmu: Apply max PA check for MMIO sptes to 32-bit KVM" failed to apply to 4.19-stable tree

The patch below does not apply to the 4.19-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 <[email protected]>.

thanks,

greg k-h

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

From e30a7d623dccdb3f880fbcad980b0cb589a1da45 Mon Sep 17 00:00:00 2001
From: Sean Christopherson <[email protected]>
Date: Tue, 7 Jan 2020 16:12:10 -0800
Subject: [PATCH] KVM: x86/mmu: Apply max PA check for MMIO sptes to 32-bit KVM

Remove the bogus 64-bit only condition from the check that disables MMIO spte optimization when the system supports the max PA, i.e. doesn't have any reserved PA bits. 32-bit KVM always uses PAE paging for the shadow MMU, and per Intel's SDM:

PAE paging translates 32-bit linear addresses to 52-bit physical addresses.

The kernel's restrictions on max physical addresses are limits on how much memory the kernel can reasonably use, not what physical addresses are supported by hardware.

index 2992ff7b42a7..57e4dbddba72 100644
@@ -6193,7 +6193,7 @@ static void kvm_set_mmio_spte_mask(void)
 	 * If reserved bit is not supported, clear the present bit to disable
 	 * mmio page fault.
 	 */
-	if (IS_ENABLED(CONFIG_X86_64) && shadow_phys_bits == 52)
+	if (shadow_phys_bits == 52)
 		mask &= ~1ull;
 
 	kvm_mmu_set_mmio_spte_mask(mask, mask, ACC_WRITE_MASK | ACC_USER_MASK);