linux-kernel - [PATCH 22/35] kvm, x86: Distinguish dmemfs page from mmio page

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Date:   Thu,  8 Oct 2020 15:54:12 +0800
From:   yulei.kernel@...il.com
To:     akpm@...ux-foundation.org, naoya.horiguchi@....com,
        viro@...iv.linux.org.uk, pbonzini@...hat.com
Cc:     linux-fsdevel@...r.kernel.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, xiaoguangrong.eric@...il.com,
        kernellwp@...il.com, lihaiwei.kernel@...il.com,
        Yulei Zhang <yuleixzhang@...cent.com>,
        Chen Zhuo <sagazchen@...cent.com>
Subject: [PATCH 22/35] kvm, x86: Distinguish dmemfs page from mmio page

From: Yulei Zhang <yuleixzhang@...cent.com>

Dmem page is pfn invalid but not mmio. Support cacheable
dmem page for kvm.

Signed-off-by: Chen Zhuo <sagazchen@...cent.com>
Signed-off-by: Yulei Zhang <yuleixzhang@...cent.com>
---
 arch/x86/kvm/mmu/mmu.c | 5 +++--
 include/linux/dmem.h   | 7 +++++++
 mm/dmem.c              | 7 +++++++
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 71aa3da2a0b7..0115c1767063 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -41,6 +41,7 @@
 #include <linux/hash.h>
 #include <linux/kern_levels.h>
 #include <linux/kthread.h>
+#include <linux/dmem.h>
 
 #include <asm/page.h>
 #include <asm/memtype.h>
@@ -2962,9 +2963,9 @@ static bool kvm_is_mmio_pfn(kvm_pfn_t pfn)
 			 */
 			(!pat_enabled() || pat_pfn_immune_to_uc_mtrr(pfn));
 
-	return !e820__mapped_raw_any(pfn_to_hpa(pfn),
+	return (!e820__mapped_raw_any(pfn_to_hpa(pfn),
 				     pfn_to_hpa(pfn + 1) - 1,
-				     E820_TYPE_RAM);
+				     E820_TYPE_RAM)) || (!is_dmem_pfn(pfn));
 }
 
 /* Bits which may be returned by set_spte() */
diff --git a/include/linux/dmem.h b/include/linux/dmem.h
index 8682d63ed43a..59d3ef14fe42 100644
--- a/include/linux/dmem.h
+++ b/include/linux/dmem.h
@@ -19,11 +19,18 @@ dmem_alloc_pages_vma(struct vm_area_struct *vma, unsigned long addr,
 		     unsigned int try_max, unsigned int *result_nr);
 
 void dmem_free_pages(phys_addr_t addr, unsigned int dpages_nr);
+bool is_dmem_pfn(unsigned long pfn);
 #define dmem_free_page(addr)	dmem_free_pages(addr, 1)
 #else
 static inline int dmem_reserve_init(void)
 {
 	return 0;
 }
+
+static inline bool is_dmem_pfn(unsigned long pfn)
+{
+	return 0;
+}
+
 #endif
 #endif	/* _LINUX_DMEM_H */
diff --git a/mm/dmem.c b/mm/dmem.c
index 2e61dbddbc62..eb6df7059cf0 100644
--- a/mm/dmem.c
+++ b/mm/dmem.c
@@ -972,3 +972,10 @@ void dmem_free_pages(phys_addr_t addr, unsigned int dpages_nr)
 }
 EXPORT_SYMBOL(dmem_free_pages);
 
+bool is_dmem_pfn(unsigned long pfn)
+{
+	struct dmem_node *dnode;
+
+	return !!find_dmem_region(__pfn_to_phys(pfn), &dnode);
+}
+EXPORT_SYMBOL(is_dmem_pfn);
-- 
2.28.0