[Devel] [PATCH RHEL8 COMMIT] ms/asm-generic/tlb: Track freeing of page-table directories in struct mmu_gather

[Konstantin Khorenko]

The commit is pushed to "branch-rh8-4.18.0-240.1.1.vz8.5.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh8-4.18.0-240.1.1.vz8.5.47
------>
commit 61853005887350303d40f2d8468905114d449066
Author: Peter Zijlstra <peterz at infradead.org>
Date:   Mon Jun 21 20:01:19 2021 +0300

    ms/asm-generic/tlb: Track freeing of page-table directories in struct mmu_gather
    
    Some architectures require different TLB invalidation instructions
    depending on whether it is only the last-level of page table being
    changed, or whether there are also changes to the intermediate
    (directory) entries higher up the tree.
    
    Add a new bit to the flags bitfield in struct mmu_gather so that the
    architecture code can operate accordingly if it's the intermediate
    levels being invalidated.
    
    Acked-by: Nicholas Piggin <npiggin at gmail.com>
    Signed-off-by: Peter Zijlstra <peterz at infradead.org>
    Signed-off-by: Will Deacon <will.deacon at arm.com>
    
    https://jira.sw.ru/browse/PSBM-101300
    (cherry picked from ms commit 22a61c3c4f1379ef8b0ce0d5cb78baf3178950e2)
    Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
    
    (cherry picked from vz7 commit ec73eb60720c3c92f3f6388a1b1988b895c1e53f)
    https://jira.sw.ru/browse/PSBM-127854
    Signed-off-by: Valeriy Vdovin <valeriy.vdovin at virtuozzo.com>
---
 include/asm-generic/tlb.h | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index 81db3c11bb11..ef44ee9c8b42 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -108,13 +108,22 @@ struct mmu_gather {
 #endif
 	unsigned long		start;
 	unsigned long		end;
-	/* we are in the middle of an operation to clear
-	 * a full mm and can make some optimizations */
-	unsigned int		fullmm : 1,
-	/* we have performed an operation which
-	 * requires a complete flush of the tlb */
-				need_flush_all : 1;
+	/*
+	 * we are in the middle of an operation to clear
+	 * a full mm and can make some optimizations
+	 */
+	unsigned int		fullmm : 1;
 
+	/*
+	 * we have performed an operation which
+	 * requires a complete flush of the tlb
+	 */
+	unsigned int		need_flush_all : 1;
+
+	/*
+	 * we have removed page directories
+	 */
+	unsigned int		freed_tables : 1;
 	struct mmu_gather_batch *active;
 	struct mmu_gather_batch	local;
 	struct page		*__pages[MMU_GATHER_BUNDLE];
@@ -148,6 +157,7 @@ static inline void __tlb_reset_range(struct mmu_gather *tlb)
 		tlb->start = TASK_SIZE;
 		tlb->end = 0;
 	}
+	tlb->freed_tables = 0;
 }
 
 static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
@@ -289,6 +299,7 @@ static inline void tlb_remove_check_page_size_change(struct mmu_gather *tlb,
 #define pte_free_tlb(tlb, ptep, address)			\
 	do {							\
 		__tlb_adjust_range(tlb, address, PAGE_SIZE);	\
+		tlb->freed_tables = 1;				\
 		__pte_free_tlb(tlb, ptep, address);		\
 	} while (0)
 #endif
@@ -297,6 +308,7 @@ static inline void tlb_remove_check_page_size_change(struct mmu_gather *tlb,
 #define pmd_free_tlb(tlb, pmdp, address)			\
 	do {							\
 		__tlb_adjust_range(tlb, address, PAGE_SIZE);		\
+		tlb->freed_tables = 1;				\
 		__pmd_free_tlb(tlb, pmdp, address);		\
 	} while (0)
 #endif
@@ -306,6 +318,7 @@ static inline void tlb_remove_check_page_size_change(struct mmu_gather *tlb,
 #define pud_free_tlb(tlb, pudp, address)			\
 	do {							\
 		__tlb_adjust_range(tlb, address, PAGE_SIZE);	\
+		tlb->freed_tables = 1;				\
 		__pud_free_tlb(tlb, pudp, address);		\
 	} while (0)
 #endif
@@ -316,6 +329,7 @@ static inline void tlb_remove_check_page_size_change(struct mmu_gather *tlb,
 #define p4d_free_tlb(tlb, pudp, address)			\
 	do {							\
 		__tlb_adjust_range(tlb, address, PAGE_SIZE);		\
+		tlb->freed_tables = 1;				\
 		__p4d_free_tlb(tlb, pudp, address);		\
 	} while (0)
 #endif