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From: Peter Xu <peterx@redhat.com>
To: linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Jason Gunthorpe <jgg@nvidia.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>,
	Matthew Wilcox <willy@infradead.org>,
	peterx@redhat.com,
	Dan Williams <dan.j.williams@intel.com>,
	"Kirill A . Shutemov" <kirill@shutemov.name>,
	Mike Rapoport <rppt@kernel.org>,
	Ingo Molnar <mingo@redhat.com>,
	Michal Hocko <mhocko@suse.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Suren Baghdasaryan <surenb@google.com>,
	Borislav Petkov <bp@alien8.de>,
	x86@kernel.org
Subject: [PATCH RFC 2/2] mm/x86/pat: Do proper PAT bit shift for large mappings
Date: Thu, 23 May 2024 18:37:45 -0400
Message-ID: <20240523223745.395337-3-peterx@redhat.com>
In-Reply-To: <20240523223745.395337-1-peterx@redhat.com>
References: <20240523223745.395337-1-peterx@redhat.com>
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For large mappings, the pgtable PAT is set on bit 12 (_PAGE_PAT_LARGE)
rather than bit 9 (_PAGE_PAT), while bit 9 is used as PAE hint.  Do proper
shifting when inject large pfn pgtable mappings to make cache mode alright.

Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: x86@kernel.org
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 mm/huge_memory.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 317de2afd371..c4a2356b1a54 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1135,7 +1135,7 @@ static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 		goto out_unlock;
 	}
 
-	entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
+	entry = pmd_mkhuge(pfn_t_pmd(pfn, pgprot_4k_2_large(prot)));
 	if (pfn_t_devmap(pfn))
 		entry = pmd_mkdevmap(entry);
 	if (write) {
@@ -1233,7 +1233,7 @@ static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
 		goto out_unlock;
 	}
 
-	entry = pud_mkhuge(pfn_t_pud(pfn, prot));
+	entry = pud_mkhuge(pfn_t_pud(pfn, pgprot_4k_2_large(prot)));
 	if (pfn_t_devmap(pfn))
 		entry = pud_mkdevmap(entry);
 	if (write) {
-- 
2.45.0