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Message-Id: <1481913337-9331-10-git-send-email-mike.kravetz@oracle.com>
Date:   Fri, 16 Dec 2016 10:35:32 -0800
From:   Mike Kravetz <mike.kravetz@...cle.com>
To:     sparclinux@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Cc:     "David S . Miller" <davem@...emloft.net>,
        Bob Picco <bob.picco@...cle.com>,
        Nitin Gupta <nitin.m.gupta@...cle.com>,
        Vijay Kumar <vijay.ac.kumar@...cle.com>,
        Julian Calaby <julian.calaby@...il.com>,
        Adam Buchbinder <adam.buchbinder@...il.com>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Michal Hocko <mhocko@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mike Kravetz <mike.kravetz@...cle.com>
Subject: [RFC PATCH 09/14] sparc64: TLB/TSB miss handling for shared context

Modifications to the fault handling code to take shared context TSB
into account.  For now, the shared context code mirrors the huge
page code.  The _PAGE_SHR_CTX_4V page flag is used to determine
which TSB should be used.

Note, TRAP_PER_CPU_TSB_HUGE_TEMP is used to stash away calculation
of a TTE address in the huge page TSB.  At present, tehre is no
similar mechanism for shared context TSB so the address must be
recalculated.

Signed-off-by: Mike Kravetz <mike.kravetz@...cle.com>
---
 arch/sparc/kernel/sun4v_tlb_miss.S |   8 +++
 arch/sparc/kernel/tsb.S            | 122 ++++++++++++++++++++++++++++++++-----
 2 files changed, 116 insertions(+), 14 deletions(-)

diff --git a/arch/sparc/kernel/sun4v_tlb_miss.S b/arch/sparc/kernel/sun4v_tlb_miss.S
index 46fbc16..c438ccc 100644
--- a/arch/sparc/kernel/sun4v_tlb_miss.S
+++ b/arch/sparc/kernel/sun4v_tlb_miss.S
@@ -152,6 +152,14 @@ sun4v_tsb_miss_common:
 	sub	%g2, TRAP_PER_CPU_FAULT_INFO, %g2
 
 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
+	/*
+	 * FIXME
+	 *
+	 * This just computes the possible huge page TSB entry.  It does
+	 * not consider the shared huge page TSB.  Also, care must be taken
+	 * so that TRAP_PER_CPU_TSB_HUGE_TEMP is only used for non-shared
+	 * huge TSB.
+	 */
 	mov	SCRATCHPAD_UTSBREG2, %g5
 	ldxa	[%g5] ASI_SCRATCHPAD, %g5
 	cmp	%g5, -1
diff --git a/arch/sparc/kernel/tsb.S b/arch/sparc/kernel/tsb.S
index 3ed3e7c..57ee5ad 100644
--- a/arch/sparc/kernel/tsb.S
+++ b/arch/sparc/kernel/tsb.S
@@ -55,6 +55,9 @@ tsb_miss_page_table_walk:
 	 */
 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
 
+	/*
+	 * First check the normal huge page TSB
+	 */
 661:	ldx		[%g7 + TRAP_PER_CPU_TSB_HUGE], %g5
 	nop
 	.section	.sun4v_2insn_patch, "ax"
@@ -64,7 +67,47 @@ tsb_miss_page_table_walk:
 	.previous
 
 	cmp		%g5, -1
-	be,pt		%xcc, 80f
+	be,pt		%xcc, chk_huge_page_shared
+	 nop
+
+	/* We need an aligned pair of registers containing 2 values
+	 * which can be easily rematerialized.  %g6 and %g7 foot the
+	 * bill just nicely.  We'll save %g6 away into %g2 for the
+	 * huge page TSB TAG comparison.
+	 *
+	 * Perform a huge page TSB lookup.
+	 */
+	mov		%g6, %g2
+
+	COMPUTE_TSB_PTR(%g5, %g4, REAL_HPAGE_SHIFT, %g6, %g7)
+
+	TSB_LOAD_QUAD(%g5, %g6)
+	cmp		%g6, %g2
+	be,a,pt		%xcc, tsb_tlb_reload
+	 mov		%g7, %g5
+
+	/*
+	 * No match, restore %g6 and %g7.
+	 * Store huge page TSB entry address
+	 *
+	 * FIXME - Look into use of TRAP_PER_CPU_TSB_HUGE_TEMP as it
+	 * is only used for regular, not shared huge pages.
+	 */
+	TRAP_LOAD_TRAP_BLOCK(%g7, %g6)
+	srlx		%g4, 22, %g6
+
+chk_huge_page_shared:
+	stx		%g5, [%g7 + TRAP_PER_CPU_TSB_HUGE_TEMP]
+
+	/*
+	 * For now (POC) only check shared context on hypervisor
+	 */
+	IF_TLB_TYPE_NOT_HYPE(%g2, huge_checks_done)
+
+	/* Check the shared huge page TSB */
+	ldx		[%g7 + TRAP_PER_CPU_TSB_HUGE_SHARED], %g5
+	cmp		%g5, -1
+	bne,pn		%xcc, huge_checks_done
 	 nop
 
 	/* We need an aligned pair of registers containing 2 values
@@ -75,15 +118,8 @@ tsb_miss_page_table_walk:
 	 * Perform a huge page TSB lookup.
 	 */
 	mov		%g6, %g2
-	and		%g5, 0x7, %g6
-	mov		512, %g7
-	andn		%g5, 0x7, %g5
-	sllx		%g7, %g6, %g7
-	srlx		%g4, REAL_HPAGE_SHIFT, %g6
-	sub		%g7, 1, %g7
-	and		%g6, %g7, %g6
-	sllx		%g6, 4, %g6
-	add		%g5, %g6, %g5
+
+	COMPUTE_TSB_PTR(%g5, %g4, REAL_HPAGE_SHIFT, %g6, %g7)
 
 	TSB_LOAD_QUAD(%g5, %g6)
 	cmp		%g6, %g2
@@ -91,25 +127,29 @@ tsb_miss_page_table_walk:
 	 mov		%g7, %g5
 
 	/* No match, remember the huge page TSB entry address,
-	 * and restore %g6 and %g7.
+	 * restore %g6 and %g7.
+	 *
+	 * NOT REALLY REMEMBERING -  See FIXME above
 	 */
 	TRAP_LOAD_TRAP_BLOCK(%g7, %g6)
 	srlx		%g4, 22, %g6
-80:	stx		%g5, [%g7 + TRAP_PER_CPU_TSB_HUGE_TEMP]
 
+huge_checks_done:
+	stx		%g5, [%g7 + TRAP_PER_CPU_TSB_HUGE_TEMP]
 #endif
 
 	ldx		[%g7 + TRAP_PER_CPU_PGD_PADDR], %g7
 
 	/* At this point we have:
-	 * %g1 --	TSB entry address
+	 * %g1 --	Base TSB entry address
 	 * %g3 --	FAULT_CODE_{D,I}TLB
 	 * %g4 --	missing virtual address
 	 * %g6 --	TAG TARGET (vaddr >> 22)
 	 * %g7 --	page table physical address
 	 *
 	 * We know that both the base PAGE_SIZE TSB and the HPAGE_SIZE
-	 * TSB both lack a matching entry.
+	 * TSB both lack a matching entry, as well as shared TSBs if
+	 * present.
 	 */
 tsb_miss_page_table_walk_sun4v_fastpath:
 	USER_PGTABLE_WALK_TL1(%g4, %g7, %g5, %g2, tsb_do_fault)
@@ -152,12 +192,42 @@ tsb_miss_page_table_walk_sun4v_fastpath:
 	 * thus handle it here.  This also makes sure that we can
 	 * allocate the TSB hash table on the correct NUMA node.
 	 */
+
+	/*
+	 * Check for shared context PTE, in this case we do not have
+	 * a saved TSB entry pointer and must compute now
+	 */
+	IF_TLB_TYPE_NOT_HYPE(%g2, no_shared_ctx_pte)
+
+	mov		_PAGE_SHR_CTX_4V, %g2
+	andcc		%g5, %g2, %g2
+	be,pn		%xcc, no_shared_ctx_pte
+
+	/*
+	 * If there was a shared context TSB, then we need to copmute the
+	 * TSB entry address.  Previously, only the non-shared context
+	 * TSB entry address was calculated.
+	 *
+	 * FIXME
+	 */
+	TRAP_LOAD_TRAP_BLOCK(%g7, %g1)
+	ldx		[%g7 + TRAP_PER_CPU_TSB_HUGE_SHARED], %g1
+	cmp		%g1, -1
+	be,pn		%xcc, no_shared_hugetlb
+	 nop
+
+	COMPUTE_TSB_PTR(%g1, %g4, REAL_HPAGE_SHIFT, %g2, %g7)
+
+	ba,a,pt %xcc,tsb_reload
+
+no_shared_ctx_pte:
 	TRAP_LOAD_TRAP_BLOCK(%g7, %g2)
 	ldx		[%g7 + TRAP_PER_CPU_TSB_HUGE_TEMP], %g1
 	cmp		%g1, -1
 	bne,pt		%xcc, 60f
 	 nop
 
+no_hugetlb:
 661:	rdpr		%pstate, %g5
 	wrpr		%g5, PSTATE_AG | PSTATE_MG, %pstate
 	.section	.sun4v_2insn_patch, "ax"
@@ -177,6 +247,30 @@ tsb_miss_page_table_walk_sun4v_fastpath:
 	ba,pt	%xcc, rtrap
 	 nop
 
+	/*
+	 * This is the same as above call to hugetlb_setup.
+	 * FIXME
+	 */
+no_shared_hugetlb:
+661:	rdpr		%pstate, %g5
+	wrpr		%g5, PSTATE_AG | PSTATE_MG, %pstate
+	.section	.sun4v_2insn_patch, "ax"
+	.word		661b
+	SET_GL(1)
+	nop
+	.previous
+
+	rdpr	%tl, %g7
+	cmp	%g7, 1
+	bne,pn	%xcc, winfix_trampoline
+	 mov	%g3, %g4
+	ba,pt	%xcc, etrap
+	 rd	%pc, %g7
+	call	hugetlb_shared_setup
+	 add	%sp, PTREGS_OFF, %o0
+	ba,pt	%xcc, rtrap
+	 nop
+
 60:
 #endif
 
-- 
2.7.4

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