[PATCH v6 00/14] KVM/X86: Introduce a new guest mapping interface

[PATCH v6 00/14] KVM/X86: Introduce a new guest mapping interface

[KarimAllah Ahmed]

Guest memory can either be directly managed by the kernel (i.e. have a "struct
page") or they can simply live outside kernel control (i.e. do not have a
"struct page"). KVM mostly support these two modes, except in a few places
where the code seems to assume that guest memory must have a "struct page".

This patchset introduces a new mapping interface to map guest memory into host
kernel memory which also supports PFN-based memory (i.e. memory without 'struct
page'). It also converts all offending code to this interface or simply
read/write directly from guest memory. Patch 2 is additionally fixing an
incorrect page release and marking the page as dirty (i.e. as a side-effect of
using the helper function to write).

As far as I can see all offending code is now fixed except the APIC-access page
which I will handle in a seperate series along with dropping
kvm_vcpu_gfn_to_page and kvm_vcpu_gpa_to_page from the internal KVM API.

The current implementation of the new API uses memremap to map memory that does
not have a "struct page". This proves to be very slow for high frequency
mappings. Since this does not affect the normal use-case where a "struct page"
is available, the performance of this API will be handled by a seperate patch
series.

So the simple way to use memory outside kernel control is:

1- Pass 'mem=' in the kernel command-line to limit the amount of memory managed 
   by the kernel.
2- Map this physical memory you want to give to the guest with:
   mmap("/dev/mem", physical_address_offset, ..)
3- Use the user-space virtual address as the "userspace_addr" field in
   KVM_SET_USER_MEMORY_REGION ioctl.

v5 -> v6:
- Added one extra patch to ensure that support for this mem= case is complete
  for x86.
- Added a helper function to check if the mapping is mapped or not.
- Added more comments on the struct.
- Setting ->page to NULL on unmap and to a poison ptr if unused during map
- Checking for map ptr before using it.
- Change kvm_vcpu_unmap to also mark page dirty for LM. That requires
  passing the vCPU pointer again to this function.

v4 -> v5:
- Introduce a new parameter 'dirty' into kvm_vcpu_unmap
- A horrible rebase due to nested.c :)
- Dropped a couple of hyperv patches as the code was fixed already as a
  side-effect of another patch.
- Added a new trivial cleanup patch.

v3 -> v4:
- Rebase
- Add a new patch to also fix the newly introduced enlightned VMCS.

v2 -> v3:
- Rebase
- Add a new patch to also fix the newly introduced shadow VMCS.

Filippo Sironi (1):
  X86/KVM: Handle PFNs outside of kernel reach when touching GPTEs

KarimAllah Ahmed (13):
  X86/nVMX: handle_vmon: Read 4 bytes from guest memory
  X86/nVMX: Update the PML table without mapping and unmapping the page
  KVM: Introduce a new guest mapping API
  X86/nVMX: handle_vmptrld: Use kvm_vcpu_map when copying VMCS12 from
    guest memory
  KVM/nVMX: Use kvm_vcpu_map when mapping the L1 MSR bitmap
  KVM/nVMX: Use kvm_vcpu_map when mapping the virtual APIC page
  KVM/nVMX: Use kvm_vcpu_map when mapping the posted interrupt
    descriptor table
  KVM/X86: Use kvm_vcpu_map in emulator_cmpxchg_emulated
  KVM/nSVM: Use the new mapping API for mapping guest memory
  KVM/nVMX: Use kvm_vcpu_map for accessing the shadow VMCS
  KVM/nVMX: Use kvm_vcpu_map for accessing the enlightened VMCS
  KVM/nVMX: Use page_address_valid in a few more locations
  kvm, x86: Properly check whether a pfn is an MMIO or not

 arch/x86/include/asm/e820/api.h |   1 +
 arch/x86/kernel/e820.c          |  18 ++++-
 arch/x86/kvm/mmu.c              |   5 +-
 arch/x86/kvm/paging_tmpl.h      |  38 +++++++---
 arch/x86/kvm/svm.c              |  97 ++++++++++++------------
 arch/x86/kvm/vmx/nested.c       | 160 +++++++++++++++-------------------------
 arch/x86/kvm/vmx/vmx.c          |  19 ++---
 arch/x86/kvm/vmx/vmx.h          |   9 ++-
 arch/x86/kvm/x86.c              |  14 ++--
 include/linux/kvm_host.h        |  28 +++++++
 virt/kvm/kvm_main.c             |  64 ++++++++++++++++
 11 files changed, 267 insertions(+), 186 deletions(-)

-- 
2.7.4

[PATCH v6 01/14] X86/nVMX: handle_vmon: Read 4 bytes from guest memory

[KarimAllah Ahmed]

Read the data directly from guest memory instead of the map->read->unmap
sequence. This also avoids using kvm_vcpu_gpa_to_page() and kmap() which
assumes that there is a "struct page" for guest memory.

Suggested-by: Jim Mattson <jmattson@google.com>
Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
Reviewed-by: Jim Mattson <jmattson@google.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

---
v1 -> v2:
- Massage commit message a bit.
---
 arch/x86/kvm/vmx/nested.c | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 8ff2052..11b44a9 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -4192,7 +4192,7 @@ static int handle_vmon(struct kvm_vcpu *vcpu)
 {
 	int ret;
 	gpa_t vmptr;
-	struct page *page;
+	uint32_t revision;
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 	const u64 VMXON_NEEDED_FEATURES = FEATURE_CONTROL_LOCKED
 		| FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX;
@@ -4241,18 +4241,10 @@ static int handle_vmon(struct kvm_vcpu *vcpu)
 	if (!PAGE_ALIGNED(vmptr) || (vmptr >> cpuid_maxphyaddr(vcpu)))
 		return nested_vmx_failInvalid(vcpu);
 
-	page = kvm_vcpu_gpa_to_page(vcpu, vmptr);
-	if (is_error_page(page))
+	if (kvm_read_guest(vcpu->kvm, vmptr, &revision, sizeof(revision)) ||
+	    revision != VMCS12_REVISION)
 		return nested_vmx_failInvalid(vcpu);
 
-	if (*(u32 *)kmap(page) != VMCS12_REVISION) {
-		kunmap(page);
-		kvm_release_page_clean(page);
-		return nested_vmx_failInvalid(vcpu);
-	}
-	kunmap(page);
-	kvm_release_page_clean(page);
-
 	vmx->nested.vmxon_ptr = vmptr;
 	ret = enter_vmx_operation(vcpu);
 	if (ret)
-- 
2.7.4

[PATCH v6 02/14] X86/nVMX: Update the PML table without mapping and unmapping the page

[KarimAllah Ahmed]

Update the PML table without mapping and unmapping the page. This also
avoids using kvm_vcpu_gpa_to_page(..) which assumes that there is a "struct
page" for guest memory.

As a side-effect of using kvm_write_guest_page the page is also properly
marked as dirty.

Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

---
v1 -> v2:
- Use kvm_write_guest_page instead of kvm_write_guest (pbonzini)
- Do not use pointer arithmetic for pml_address (pbonzini)
---
 arch/x86/kvm/vmx/vmx.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 4341175..a3da75a 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7206,9 +7206,7 @@ static int vmx_write_pml_buffer(struct kvm_vcpu *vcpu)
 {
 	struct vmcs12 *vmcs12;
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
-	gpa_t gpa;
-	struct page *page = NULL;
-	u64 *pml_address;
+	gpa_t gpa, dst;
 
 	if (is_guest_mode(vcpu)) {
 		WARN_ON_ONCE(vmx->nested.pml_full);
@@ -7228,15 +7226,13 @@ static int vmx_write_pml_buffer(struct kvm_vcpu *vcpu)
 		}
 
 		gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS) & ~0xFFFull;
+		dst = vmcs12->pml_address + sizeof(u64) * vmcs12->guest_pml_index;
 
-		page = kvm_vcpu_gpa_to_page(vcpu, vmcs12->pml_address);
-		if (is_error_page(page))
+		if (kvm_write_guest_page(vcpu->kvm, gpa_to_gfn(dst), &gpa,
+					 offset_in_page(dst), sizeof(gpa)))
 			return 0;
 
-		pml_address = kmap(page);
-		pml_address[vmcs12->guest_pml_index--] = gpa;
-		kunmap(page);
-		kvm_release_page_clean(page);
+		vmcs12->guest_pml_index--;
 	}
 
 	return 0;
-- 
2.7.4

[PATCH v6 03/14] X86/KVM: Handle PFNs outside of kernel reach when touching GPTEs

[KarimAllah Ahmed]

From: Filippo Sironi <sironi@amazon.de>

cmpxchg_gpte() calls get_user_pages_fast() to retrieve the number of
pages and the respective struct page to map in the kernel virtual
address space.
This doesn't work if get_user_pages_fast() is invoked with a userspace
virtual address that's backed by PFNs outside of kernel reach (e.g., when
limiting the kernel memory with mem= in the command line and using
/dev/mem to map memory).

If get_user_pages_fast() fails, look up the VMA that back the userspace
virtual address, compute the PFN and the physical address, and map it in
the kernel virtual address space with memremap().

Signed-off-by: Filippo Sironi <sironi@amazon.de>
Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
---
 arch/x86/kvm/paging_tmpl.h | 38 +++++++++++++++++++++++++++++---------
 1 file changed, 29 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 6bdca39..c40af67 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -141,15 +141,35 @@ static int FNAME(cmpxchg_gpte)(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
 	struct page *page;
 
 	npages = get_user_pages_fast((unsigned long)ptep_user, 1, 1, &page);
-	/* Check if the user is doing something meaningless. */
-	if (unlikely(npages != 1))
-		return -EFAULT;
-
-	table = kmap_atomic(page);
-	ret = CMPXCHG(&table[index], orig_pte, new_pte);
-	kunmap_atomic(table);
-
-	kvm_release_page_dirty(page);
+	if (likely(npages == 1)) {
+		table = kmap_atomic(page);
+		ret = CMPXCHG(&table[index], orig_pte, new_pte);
+		kunmap_atomic(table);
+
+		kvm_release_page_dirty(page);
+	} else {
+		struct vm_area_struct *vma;
+		unsigned long vaddr = (unsigned long)ptep_user & PAGE_MASK;
+		unsigned long pfn;
+		unsigned long paddr;
+
+		down_read(&current->mm->mmap_sem);
+		vma = find_vma_intersection(current->mm, vaddr, vaddr + PAGE_SIZE);
+		if (!vma || !(vma->vm_flags & VM_PFNMAP)) {
+			up_read(&current->mm->mmap_sem);
+			return -EFAULT;
+		}
+		pfn = ((vaddr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
+		paddr = pfn << PAGE_SHIFT;
+		table = memremap(paddr, PAGE_SIZE, MEMREMAP_WB);
+		if (!table) {
+			up_read(&current->mm->mmap_sem);
+			return -EFAULT;
+		}
+		ret = CMPXCHG(&table[index], orig_pte, new_pte);
+		memunmap(table);
+		up_read(&current->mm->mmap_sem);
+	}
 
 	return (ret != orig_pte);
 }
-- 
2.7.4

[PATCH v6 04/14] KVM: Introduce a new guest mapping API

[KarimAllah Ahmed]

In KVM, specially for nested guests, there is a dominant pattern of:

	=> map guest memory -> do_something -> unmap guest memory

In addition to all this unnecessarily noise in the code due to boiler plate
code, most of the time the mapping function does not properly handle memory
that is not backed by "struct page". This new guest mapping API encapsulate
most of this boiler plate code and also handles guest memory that is not
backed by "struct page".

The current implementation of this API is using memremap for memory that is
not backed by a "struct page" which would lead to a huge slow-down if it
was used for high-frequency mapping operations. The API does not have any
effect on current setups where guest memory is backed by a "struct page".
Further patches are going to also introduce a pfn-cache which would
significantly improve the performance of the memremap case.

Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

---
v5 -> v6:
- Added a helper function to check if the mapping is mapped or not.
- Added more comments on the struct.
- Setting ->page to NULL on unmap and to a poison ptr if unused during map.
- Checking for map ptr before using it.
- Change kvm_vcpu_unmap to also mark page dirty for LM. That requires
  passing the vCPU pointer again to this function.
v3 -> v4:
- Update the commit message.
v1 -> v2:
- Drop the caching optimization (pbonzini)
- Use 'hva' instead of 'kaddr' (pbonzini)
- Return 0/-EINVAL/-EFAULT instead of true/false. -EFAULT will be used for
  AMD patch (pbonzini)
- Introduce __kvm_map_gfn which accepts a memory slot and use it (pbonzini)
- Only clear map->hva instead of memsetting the whole structure.
- Drop kvm_vcpu_map_valid since it is no longer used.
- Fix EXPORT_MODULE naming.
---
 include/linux/kvm_host.h | 28 +++++++++++++++++++++
 virt/kvm/kvm_main.c      | 64 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 92 insertions(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index c38cc5e..15879ed 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -205,6 +205,32 @@ enum {
 	READING_SHADOW_PAGE_TABLES,
 };
 
+#define KVM_UNMAPPED_PAGE	((void *) 0x500 + POISON_POINTER_DELTA)
+
+struct kvm_host_map {
+	/*
+	 * Only valid if the 'pfn' is managed by the host kernel (i.e. There is
+	 * a 'struct page' for it. When using mem= kernel parameter some memory
+	 * can be used as guest memory but they are not managed by host
+	 * kernel).
+	 * If 'pfn' is not managed by the host kernel, this field is
+	 * initialized to KVM_UNMAPPED_PAGE.
+	 */
+	struct page *page;
+	void *hva;
+	kvm_pfn_t pfn;
+	kvm_pfn_t gfn;
+};
+
+/*
+ * Used to check if the mapping is valid or not. Never use 'kvm_host_map'
+ * directly to check for that.
+ */
+static inline bool kvm_vcpu_mapped(struct kvm_host_map *map)
+{
+	return !!map->hva;
+}
+
 /*
  * Sometimes a large or cross-page mmio needs to be broken up into separate
  * exits for userspace servicing.
@@ -710,7 +736,9 @@ struct kvm_memslots *kvm_vcpu_memslots(struct kvm_vcpu *vcpu);
 struct kvm_memory_slot *kvm_vcpu_gfn_to_memslot(struct kvm_vcpu *vcpu, gfn_t gfn);
 kvm_pfn_t kvm_vcpu_gfn_to_pfn_atomic(struct kvm_vcpu *vcpu, gfn_t gfn);
 kvm_pfn_t kvm_vcpu_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn);
+int kvm_vcpu_map(struct kvm_vcpu *vcpu, gpa_t gpa, struct kvm_host_map *map);
 struct page *kvm_vcpu_gfn_to_page(struct kvm_vcpu *vcpu, gfn_t gfn);
+void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty);
 unsigned long kvm_vcpu_gfn_to_hva(struct kvm_vcpu *vcpu, gfn_t gfn);
 unsigned long kvm_vcpu_gfn_to_hva_prot(struct kvm_vcpu *vcpu, gfn_t gfn, bool *writable);
 int kvm_vcpu_read_guest_page(struct kvm_vcpu *vcpu, gfn_t gfn, void *data, int offset,
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 5ecea81..da3a8fc 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1738,6 +1738,70 @@ struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
 }
 EXPORT_SYMBOL_GPL(gfn_to_page);
 
+static int __kvm_map_gfn(struct kvm_memory_slot *slot, gfn_t gfn,
+			 struct kvm_host_map *map)
+{
+	kvm_pfn_t pfn;
+	void *hva = NULL;
+	struct page *page = KVM_UNMAPPED_PAGE;
+
+	if (!map)
+		return -EINVAL;
+
+	pfn = gfn_to_pfn_memslot(slot, gfn);
+	if (is_error_noslot_pfn(pfn))
+		return -EINVAL;
+
+	if (pfn_valid(pfn)) {
+		page = pfn_to_page(pfn);
+		hva = kmap(page);
+	} else {
+		hva = memremap(pfn_to_hpa(pfn), PAGE_SIZE, MEMREMAP_WB);
+	}
+
+	if (!hva)
+		return -EFAULT;
+
+	map->page = page;
+	map->hva = hva;
+	map->pfn = pfn;
+	map->gfn = gfn;
+
+	return 0;
+}
+
+int kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map)
+{
+	return __kvm_map_gfn(kvm_vcpu_gfn_to_memslot(vcpu, gfn), gfn, map);
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_map);
+
+void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map,
+		    bool dirty)
+{
+	if (!map)
+		return;
+
+	if (!map->hva)
+		return;
+
+	if (map->page)
+		kunmap(map->page);
+	else
+		memunmap(map->hva);
+
+	if (dirty) {
+		kvm_vcpu_mark_page_dirty(vcpu, map->gfn);
+		kvm_release_pfn_dirty(map->pfn);
+	} else {
+		kvm_release_pfn_clean(map->pfn);
+	}
+
+	map->hva = NULL;
+	map->page = NULL;
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_unmap);
+
 struct page *kvm_vcpu_gfn_to_page(struct kvm_vcpu *vcpu, gfn_t gfn)
 {
 	kvm_pfn_t pfn;
-- 
2.7.4

[PATCH v6 05/14] X86/nVMX: handle_vmptrld: Use kvm_vcpu_map when copying VMCS12 from guest memory

[KarimAllah Ahmed]

Use kvm_vcpu_map to the map the VMCS12 from guest memory because
kvm_vcpu_gpa_to_page() and kmap() will only work for guest memory that has
a "struct page".

Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
v4 -> v5:
- Switch to the new guest mapping API instead of reading directly from
  guest.
- unmap with dirty flag
v3 -> v4:
- Return VMXERR_VMPTRLD_INCORRECT_VMCS_REVISION_ID on failure (jmattson@)
v1 -> v2:
- Massage commit message a bit.
---
 arch/x86/kvm/vmx/nested.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 11b44a9..8fc327f 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -4521,11 +4521,10 @@ static int handle_vmptrld(struct kvm_vcpu *vcpu)
 		return 1;
 
 	if (vmx->nested.current_vmptr != vmptr) {
+		struct kvm_host_map map;
 		struct vmcs12 *new_vmcs12;
-		struct page *page;
 
-		page = kvm_vcpu_gpa_to_page(vcpu, vmptr);
-		if (is_error_page(page)) {
+		if (kvm_vcpu_map(vcpu, gpa_to_gfn(vmptr), &map)) {
 			/*
 			 * Reads from an unbacked page return all 1s,
 			 * which means that the 32 bits located at the
@@ -4535,12 +4534,13 @@ static int handle_vmptrld(struct kvm_vcpu *vcpu)
 			return nested_vmx_failValid(vcpu,
 				VMXERR_VMPTRLD_INCORRECT_VMCS_REVISION_ID);
 		}
-		new_vmcs12 = kmap(page);
+
+		new_vmcs12 = map.hva;
+
 		if (new_vmcs12->hdr.revision_id != VMCS12_REVISION ||
 		    (new_vmcs12->hdr.shadow_vmcs &&
 		     !nested_cpu_has_vmx_shadow_vmcs(vcpu))) {
-			kunmap(page);
-			kvm_release_page_clean(page);
+			kvm_vcpu_unmap(vcpu, &map, false);
 			return nested_vmx_failValid(vcpu,
 				VMXERR_VMPTRLD_INCORRECT_VMCS_REVISION_ID);
 		}
@@ -4552,8 +4552,7 @@ static int handle_vmptrld(struct kvm_vcpu *vcpu)
 		 * cached.
 		 */
 		memcpy(vmx->nested.cached_vmcs12, new_vmcs12, VMCS12_SIZE);
-		kunmap(page);
-		kvm_release_page_clean(page);
+		kvm_vcpu_unmap(vcpu, &map, false);
 
 		set_current_vmptr(vmx, vmptr);
 	}
-- 
2.7.4

[PATCH v6 06/14] KVM/nVMX: Use kvm_vcpu_map when mapping the L1 MSR bitmap

[KarimAllah Ahmed]

Use kvm_vcpu_map when mapping the L1 MSR bitmap since using
kvm_vcpu_gpa_to_page() and kmap() will only work for guest memory that has
a "struct page".

Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
---
v4 -> v5:
- unmap with dirty flag

v1 -> v2:
- Do not change the lifecycle of the mapping (pbonzini)
---
 arch/x86/kvm/vmx/nested.c | 11 +++++------
 arch/x86/kvm/vmx/vmx.h    |  3 +++
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 8fc327f..1813211 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -507,9 +507,10 @@ static inline bool nested_vmx_prepare_msr_bitmap(struct kvm_vcpu *vcpu,
 						 struct vmcs12 *vmcs12)
 {
 	int msr;
-	struct page *page;
 	unsigned long *msr_bitmap_l1;
 	unsigned long *msr_bitmap_l0 = to_vmx(vcpu)->nested.vmcs02.msr_bitmap;
+	struct kvm_host_map *map = &to_vmx(vcpu)->nested.msr_bitmap_map;
+
 	/*
 	 * pred_cmd & spec_ctrl are trying to verify two things:
 	 *
@@ -535,11 +536,10 @@ static inline bool nested_vmx_prepare_msr_bitmap(struct kvm_vcpu *vcpu,
 	    !pred_cmd && !spec_ctrl)
 		return false;
 
-	page = kvm_vcpu_gpa_to_page(vcpu, vmcs12->msr_bitmap);
-	if (is_error_page(page))
+	if (kvm_vcpu_map(vcpu, gpa_to_gfn(vmcs12->msr_bitmap), map))
 		return false;
 
-	msr_bitmap_l1 = (unsigned long *)kmap(page);
+	msr_bitmap_l1 = (unsigned long *)map->hva;
 	if (nested_cpu_has_apic_reg_virt(vmcs12)) {
 		/*
 		 * L0 need not intercept reads for MSRs between 0x800 and 0x8ff, it
@@ -587,8 +587,7 @@ static inline bool nested_vmx_prepare_msr_bitmap(struct kvm_vcpu *vcpu,
 					MSR_IA32_PRED_CMD,
 					MSR_TYPE_W);
 
-	kunmap(page);
-	kvm_release_page_clean(page);
+	kvm_vcpu_unmap(vcpu, &to_vmx(vcpu)->nested.msr_bitmap_map, false);
 
 	return true;
 }
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 9932895..6fb69d8 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -144,6 +144,9 @@ struct nested_vmx {
 	struct page *apic_access_page;
 	struct page *virtual_apic_page;
 	struct page *pi_desc_page;
+
+	struct kvm_host_map msr_bitmap_map;
+
 	struct pi_desc *pi_desc;
 	bool pi_pending;
 	u16 posted_intr_nv;
-- 
2.7.4

[PATCH v6 07/14] KVM/nVMX: Use kvm_vcpu_map when mapping the virtual APIC page

[KarimAllah Ahmed]

Use kvm_vcpu_map when mapping the virtual APIC page since using
kvm_vcpu_gpa_to_page() and kmap() will only work for guest memory that has
a "struct page".

One additional semantic change is that the virtual host mapping lifecycle
has changed a bit. It now has the same lifetime of the pinning of the
virtual APIC page on the host side.

Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
v4 -> v5:
- unmap with dirty flag

v1 -> v2:
- Do not change the lifecycle of the mapping (pbonzini)
- Use pfn_to_hpa instead of gfn_to_gpa
---
 arch/x86/kvm/vmx/nested.c | 32 +++++++++++---------------------
 arch/x86/kvm/vmx/vmx.c    |  5 ++---
 arch/x86/kvm/vmx/vmx.h    |  2 +-
 3 files changed, 14 insertions(+), 25 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 1813211..31b352c 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -229,10 +229,7 @@ static void free_nested(struct kvm_vcpu *vcpu)
 		kvm_release_page_dirty(vmx->nested.apic_access_page);
 		vmx->nested.apic_access_page = NULL;
 	}
-	if (vmx->nested.virtual_apic_page) {
-		kvm_release_page_dirty(vmx->nested.virtual_apic_page);
-		vmx->nested.virtual_apic_page = NULL;
-	}
+	kvm_vcpu_unmap(vcpu, &vmx->nested.virtual_apic_map, true);
 	if (vmx->nested.pi_desc_page) {
 		kunmap(vmx->nested.pi_desc_page);
 		kvm_release_page_dirty(vmx->nested.pi_desc_page);
@@ -2817,6 +2814,7 @@ static void nested_get_vmcs12_pages(struct kvm_vcpu *vcpu)
 {
 	struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
+	struct kvm_host_map *map;
 	struct page *page;
 	u64 hpa;
 
@@ -2849,11 +2847,7 @@ static void nested_get_vmcs12_pages(struct kvm_vcpu *vcpu)
 	}
 
 	if (nested_cpu_has(vmcs12, CPU_BASED_TPR_SHADOW)) {
-		if (vmx->nested.virtual_apic_page) { /* shouldn't happen */
-			kvm_release_page_dirty(vmx->nested.virtual_apic_page);
-			vmx->nested.virtual_apic_page = NULL;
-		}
-		page = kvm_vcpu_gpa_to_page(vcpu, vmcs12->virtual_apic_page_addr);
+		map = &vmx->nested.virtual_apic_map;
 
 		/*
 		 * If translation failed, VM entry will fail because
@@ -2868,11 +2862,9 @@ static void nested_get_vmcs12_pages(struct kvm_vcpu *vcpu)
 		 * control.  But such a configuration is useless, so
 		 * let's keep the code simple.
 		 */
-		if (!is_error_page(page)) {
-			vmx->nested.virtual_apic_page = page;
-			hpa = page_to_phys(vmx->nested.virtual_apic_page);
-			vmcs_write64(VIRTUAL_APIC_PAGE_ADDR, hpa);
-		}
+		if (!kvm_vcpu_map(vcpu, gpa_to_gfn(vmcs12->virtual_apic_page_addr), map))
+			vmcs_write64(VIRTUAL_APIC_PAGE_ADDR, pfn_to_hpa(map->pfn));
+
 	}
 
 	if (nested_cpu_has_posted_intr(vmcs12)) {
@@ -3279,11 +3271,12 @@ static void vmx_complete_nested_posted_interrupt(struct kvm_vcpu *vcpu)
 
 	max_irr = find_last_bit((unsigned long *)vmx->nested.pi_desc->pir, 256);
 	if (max_irr != 256) {
-		vapic_page = kmap(vmx->nested.virtual_apic_page);
+		vapic_page = vmx->nested.virtual_apic_map.hva;
+		if (!vapic_page)
+			return;
+
 		__kvm_apic_update_irr(vmx->nested.pi_desc->pir,
 			vapic_page, &max_irr);
-		kunmap(vmx->nested.virtual_apic_page);
-
 		status = vmcs_read16(GUEST_INTR_STATUS);
 		if ((u8)max_irr > ((u8)status & 0xff)) {
 			status &= ~0xff;
@@ -3917,10 +3910,7 @@ void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
 		kvm_release_page_dirty(vmx->nested.apic_access_page);
 		vmx->nested.apic_access_page = NULL;
 	}
-	if (vmx->nested.virtual_apic_page) {
-		kvm_release_page_dirty(vmx->nested.virtual_apic_page);
-		vmx->nested.virtual_apic_page = NULL;
-	}
+	kvm_vcpu_unmap(vcpu, &vmx->nested.virtual_apic_map, true);
 	if (vmx->nested.pi_desc_page) {
 		kunmap(vmx->nested.pi_desc_page);
 		kvm_release_page_dirty(vmx->nested.pi_desc_page);
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index a3da75a..ea9cffc 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -3627,14 +3627,13 @@ static bool vmx_guest_apic_has_interrupt(struct kvm_vcpu *vcpu)
 
 	if (WARN_ON_ONCE(!is_guest_mode(vcpu)) ||
 		!nested_cpu_has_vid(get_vmcs12(vcpu)) ||
-		WARN_ON_ONCE(!vmx->nested.virtual_apic_page))
+		WARN_ON_ONCE(!vmx->nested.virtual_apic_map.gfn))
 		return false;
 
 	rvi = vmx_get_rvi();
 
-	vapic_page = kmap(vmx->nested.virtual_apic_page);
+	vapic_page = vmx->nested.virtual_apic_map.hva;
 	vppr = *((u32 *)(vapic_page + APIC_PROCPRI));
-	kunmap(vmx->nested.virtual_apic_page);
 
 	return ((rvi & 0xf0) > (vppr & 0xf0));
 }
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 6fb69d8..f618f52 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -142,7 +142,7 @@ struct nested_vmx {
 	 * pointers, so we must keep them pinned while L2 runs.
 	 */
 	struct page *apic_access_page;
-	struct page *virtual_apic_page;
+	struct kvm_host_map virtual_apic_map;
 	struct page *pi_desc_page;
 
 	struct kvm_host_map msr_bitmap_map;
-- 
2.7.4

[PATCH v6 08/14] KVM/nVMX: Use kvm_vcpu_map when mapping the posted interrupt descriptor table

[KarimAllah Ahmed]

Use kvm_vcpu_map when mapping the posted interrupt descriptor table since
using kvm_vcpu_gpa_to_page() and kmap() will only work for guest memory
that has a "struct page".

One additional semantic change is that the virtual host mapping lifecycle
has changed a bit. It now has the same lifetime of the pinning of the
interrupt descriptor table page on the host side.

Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
v4 -> v5:
- unmap with dirty flag

v1 -> v2:
- Do not change the lifecycle of the mapping (pbonzini)
---
 arch/x86/kvm/vmx/nested.c | 43 ++++++++++++-------------------------------
 arch/x86/kvm/vmx/vmx.h    |  2 +-
 2 files changed, 13 insertions(+), 32 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 31b352c..53b1063 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -230,12 +230,8 @@ static void free_nested(struct kvm_vcpu *vcpu)
 		vmx->nested.apic_access_page = NULL;
 	}
 	kvm_vcpu_unmap(vcpu, &vmx->nested.virtual_apic_map, true);
-	if (vmx->nested.pi_desc_page) {
-		kunmap(vmx->nested.pi_desc_page);
-		kvm_release_page_dirty(vmx->nested.pi_desc_page);
-		vmx->nested.pi_desc_page = NULL;
-		vmx->nested.pi_desc = NULL;
-	}
+	kvm_vcpu_unmap(vcpu, &vmx->nested.pi_desc_map, true);
+	vmx->nested.pi_desc = NULL;
 
 	kvm_mmu_free_roots(vcpu, &vcpu->arch.guest_mmu, KVM_MMU_ROOTS_ALL);
 
@@ -2868,26 +2864,15 @@ static void nested_get_vmcs12_pages(struct kvm_vcpu *vcpu)
 	}
 
 	if (nested_cpu_has_posted_intr(vmcs12)) {
-		if (vmx->nested.pi_desc_page) { /* shouldn't happen */
-			kunmap(vmx->nested.pi_desc_page);
-			kvm_release_page_dirty(vmx->nested.pi_desc_page);
-			vmx->nested.pi_desc_page = NULL;
-			vmx->nested.pi_desc = NULL;
-			vmcs_write64(POSTED_INTR_DESC_ADDR, -1ull);
+		map = &vmx->nested.pi_desc_map;
+
+		if (!kvm_vcpu_map(vcpu, gpa_to_gfn(vmcs12->posted_intr_desc_addr), map)) {
+			vmx->nested.pi_desc =
+				(struct pi_desc *)(((void *)map->hva) +
+				offset_in_page(vmcs12->posted_intr_desc_addr));
+			vmcs_write64(POSTED_INTR_DESC_ADDR,
+				     pfn_to_hpa(map->pfn) + offset_in_page(vmcs12->posted_intr_desc_addr));
 		}
-		page = kvm_vcpu_gpa_to_page(vcpu, vmcs12->posted_intr_desc_addr);
-		if (is_error_page(page))
-			return;
-		vmx->nested.pi_desc_page = page;
-		vmx->nested.pi_desc = kmap(vmx->nested.pi_desc_page);
-		vmx->nested.pi_desc =
-			(struct pi_desc *)((void *)vmx->nested.pi_desc +
-			(unsigned long)(vmcs12->posted_intr_desc_addr &
-			(PAGE_SIZE - 1)));
-		vmcs_write64(POSTED_INTR_DESC_ADDR,
-			page_to_phys(vmx->nested.pi_desc_page) +
-			(unsigned long)(vmcs12->posted_intr_desc_addr &
-			(PAGE_SIZE - 1)));
 	}
 	if (nested_vmx_prepare_msr_bitmap(vcpu, vmcs12))
 		vmcs_set_bits(CPU_BASED_VM_EXEC_CONTROL,
@@ -3911,12 +3896,8 @@ void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
 		vmx->nested.apic_access_page = NULL;
 	}
 	kvm_vcpu_unmap(vcpu, &vmx->nested.virtual_apic_map, true);
-	if (vmx->nested.pi_desc_page) {
-		kunmap(vmx->nested.pi_desc_page);
-		kvm_release_page_dirty(vmx->nested.pi_desc_page);
-		vmx->nested.pi_desc_page = NULL;
-		vmx->nested.pi_desc = NULL;
-	}
+	kvm_vcpu_unmap(vcpu, &vmx->nested.pi_desc_map, true);
+	vmx->nested.pi_desc = NULL;
 
 	/*
 	 * We are now running in L2, mmu_notifier will force to reload the
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index f618f52..bd04725 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -143,7 +143,7 @@ struct nested_vmx {
 	 */
 	struct page *apic_access_page;
 	struct kvm_host_map virtual_apic_map;
-	struct page *pi_desc_page;
+	struct kvm_host_map pi_desc_map;
 
 	struct kvm_host_map msr_bitmap_map;
 
-- 
2.7.4

[PATCH v6 09/14] KVM/X86: Use kvm_vcpu_map in emulator_cmpxchg_emulated

[KarimAllah Ahmed]

Use kvm_vcpu_map in emulator_cmpxchg_emulated since using
kvm_vcpu_gpa_to_page() and kmap() will only work for guest memory that has
a "struct page".

Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
Reviewed-by: Konrad Rzeszutek Wilk <kjonrad.wilk@oracle.com>
---
v5 -> v6:
- Remove explicit call to dirty the page. It is now done by kvm_vcpu_unmap

v4 -> v5:
- unmap with dirty flag

v1 -> v2:
- Update to match the new API return codes
---
 arch/x86/kvm/x86.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 3d27206..f6800e0 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5494,9 +5494,9 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt,
 				     unsigned int bytes,
 				     struct x86_exception *exception)
 {
+	struct kvm_host_map map;
 	struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
 	gpa_t gpa;
-	struct page *page;
 	char *kaddr;
 	bool exchanged;
 
@@ -5513,12 +5513,11 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt,
 	if (((gpa + bytes - 1) & PAGE_MASK) != (gpa & PAGE_MASK))
 		goto emul_write;
 
-	page = kvm_vcpu_gfn_to_page(vcpu, gpa >> PAGE_SHIFT);
-	if (is_error_page(page))
+	if (kvm_vcpu_map(vcpu, gpa_to_gfn(gpa), &map))
 		goto emul_write;
 
-	kaddr = kmap_atomic(page);
-	kaddr += offset_in_page(gpa);
+	kaddr = map.hva + offset_in_page(gpa);
+
 	switch (bytes) {
 	case 1:
 		exchanged = CMPXCHG_TYPE(u8, kaddr, old, new);
@@ -5535,13 +5534,12 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt,
 	default:
 		BUG();
 	}
-	kunmap_atomic(kaddr);
-	kvm_release_page_dirty(page);
+
+	kvm_vcpu_unmap(vcpu, &map, true);
 
 	if (!exchanged)
 		return X86EMUL_CMPXCHG_FAILED;
 
-	kvm_vcpu_mark_page_dirty(vcpu, gpa >> PAGE_SHIFT);
 	kvm_page_track_write(vcpu, gpa, new, bytes);
 
 	return X86EMUL_CONTINUE;
-- 
2.7.4

[PATCH v6 10/14] KVM/nSVM: Use the new mapping API for mapping guest memory

[KarimAllah Ahmed]

Use the new mapping API for mapping guest memory to avoid depending on
"struct page".

Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
v4 -> v5:
- unmap with dirty flag
---
 arch/x86/kvm/svm.c | 97 +++++++++++++++++++++++++++---------------------------
 1 file changed, 49 insertions(+), 48 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index f13a3a2..d30a35b 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3062,32 +3062,6 @@ static inline bool nested_svm_nmi(struct vcpu_svm *svm)
 	return false;
 }
 
-static void *nested_svm_map(struct vcpu_svm *svm, u64 gpa, struct page **_page)
-{
-	struct page *page;
-
-	might_sleep();
-
-	page = kvm_vcpu_gfn_to_page(&svm->vcpu, gpa >> PAGE_SHIFT);
-	if (is_error_page(page))
-		goto error;
-
-	*_page = page;
-
-	return kmap(page);
-
-error:
-	kvm_inject_gp(&svm->vcpu, 0);
-
-	return NULL;
-}
-
-static void nested_svm_unmap(struct page *page)
-{
-	kunmap(page);
-	kvm_release_page_dirty(page);
-}
-
 static int nested_svm_intercept_ioio(struct vcpu_svm *svm)
 {
 	unsigned port, size, iopm_len;
@@ -3290,10 +3264,11 @@ static inline void copy_vmcb_control_area(struct vmcb *dst_vmcb, struct vmcb *fr
 
 static int nested_svm_vmexit(struct vcpu_svm *svm)
 {
+	int rc;
 	struct vmcb *nested_vmcb;
 	struct vmcb *hsave = svm->nested.hsave;
 	struct vmcb *vmcb = svm->vmcb;
-	struct page *page;
+	struct kvm_host_map map;
 
 	trace_kvm_nested_vmexit_inject(vmcb->control.exit_code,
 				       vmcb->control.exit_info_1,
@@ -3302,9 +3277,14 @@ static int nested_svm_vmexit(struct vcpu_svm *svm)
 				       vmcb->control.exit_int_info_err,
 				       KVM_ISA_SVM);
 
-	nested_vmcb = nested_svm_map(svm, svm->nested.vmcb, &page);
-	if (!nested_vmcb)
+	rc = kvm_vcpu_map(&svm->vcpu, gfn_to_gpa(svm->nested.vmcb), &map);
+	if (rc) {
+		if (rc == -EINVAL)
+			kvm_inject_gp(&svm->vcpu, 0);
 		return 1;
+	}
+
+	nested_vmcb = map.hva;
 
 	/* Exit Guest-Mode */
 	leave_guest_mode(&svm->vcpu);
@@ -3408,7 +3388,7 @@ static int nested_svm_vmexit(struct vcpu_svm *svm)
 
 	mark_all_dirty(svm->vmcb);
 
-	nested_svm_unmap(page);
+	kvm_vcpu_unmap(&svm->vcpu, &map, true);
 
 	nested_svm_uninit_mmu_context(&svm->vcpu);
 	kvm_mmu_reset_context(&svm->vcpu);
@@ -3474,7 +3454,7 @@ static bool nested_vmcb_checks(struct vmcb *vmcb)
 }
 
 static void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
-				 struct vmcb *nested_vmcb, struct page *page)
+				 struct vmcb *nested_vmcb, struct kvm_host_map *map)
 {
 	if (kvm_get_rflags(&svm->vcpu) & X86_EFLAGS_IF)
 		svm->vcpu.arch.hflags |= HF_HIF_MASK;
@@ -3558,7 +3538,7 @@ static void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
 	svm->vmcb->control.pause_filter_thresh =
 		nested_vmcb->control.pause_filter_thresh;
 
-	nested_svm_unmap(page);
+	kvm_vcpu_unmap(&svm->vcpu, map, true);
 
 	/* Enter Guest-Mode */
 	enter_guest_mode(&svm->vcpu);
@@ -3578,17 +3558,23 @@ static void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
 
 static bool nested_svm_vmrun(struct vcpu_svm *svm)
 {
+	int rc;
 	struct vmcb *nested_vmcb;
 	struct vmcb *hsave = svm->nested.hsave;
 	struct vmcb *vmcb = svm->vmcb;
-	struct page *page;
+	struct kvm_host_map map;
 	u64 vmcb_gpa;
 
 	vmcb_gpa = svm->vmcb->save.rax;
 
-	nested_vmcb = nested_svm_map(svm, svm->vmcb->save.rax, &page);
-	if (!nested_vmcb)
+	rc = kvm_vcpu_map(&svm->vcpu, gfn_to_gpa(vmcb_gpa), &map);
+	if (rc) {
+		if (rc == -EINVAL)
+			kvm_inject_gp(&svm->vcpu, 0);
 		return false;
+	}
+
+	nested_vmcb = map.hva;
 
 	if (!nested_vmcb_checks(nested_vmcb)) {
 		nested_vmcb->control.exit_code    = SVM_EXIT_ERR;
@@ -3596,7 +3582,7 @@ static bool nested_svm_vmrun(struct vcpu_svm *svm)
 		nested_vmcb->control.exit_info_1  = 0;
 		nested_vmcb->control.exit_info_2  = 0;
 
-		nested_svm_unmap(page);
+		kvm_vcpu_unmap(&svm->vcpu, &map, true);
 
 		return false;
 	}
@@ -3640,7 +3626,7 @@ static bool nested_svm_vmrun(struct vcpu_svm *svm)
 
 	copy_vmcb_control_area(hsave, vmcb);
 
-	enter_svm_guest_mode(svm, vmcb_gpa, nested_vmcb, page);
+	enter_svm_guest_mode(svm, vmcb_gpa, nested_vmcb, &map);
 
 	return true;
 }
@@ -3664,21 +3650,26 @@ static void nested_svm_vmloadsave(struct vmcb *from_vmcb, struct vmcb *to_vmcb)
 static int vmload_interception(struct vcpu_svm *svm)
 {
 	struct vmcb *nested_vmcb;
-	struct page *page;
+	struct kvm_host_map map;
 	int ret;
 
 	if (nested_svm_check_permissions(svm))
 		return 1;
 
-	nested_vmcb = nested_svm_map(svm, svm->vmcb->save.rax, &page);
-	if (!nested_vmcb)
+	ret = kvm_vcpu_map(&svm->vcpu, gpa_to_gfn(svm->vmcb->save.rax), &map);
+	if (ret) {
+		if (ret == -EINVAL)
+			kvm_inject_gp(&svm->vcpu, 0);
 		return 1;
+	}
+
+	nested_vmcb = map.hva;
 
 	svm->next_rip = kvm_rip_read(&svm->vcpu) + 3;
 	ret = kvm_skip_emulated_instruction(&svm->vcpu);
 
 	nested_svm_vmloadsave(nested_vmcb, svm->vmcb);
-	nested_svm_unmap(page);
+	kvm_vcpu_unmap(&svm->vcpu, &map, true);
 
 	return ret;
 }
@@ -3686,21 +3677,26 @@ static int vmload_interception(struct vcpu_svm *svm)
 static int vmsave_interception(struct vcpu_svm *svm)
 {
 	struct vmcb *nested_vmcb;
-	struct page *page;
+	struct kvm_host_map map;
 	int ret;
 
 	if (nested_svm_check_permissions(svm))
 		return 1;
 
-	nested_vmcb = nested_svm_map(svm, svm->vmcb->save.rax, &page);
-	if (!nested_vmcb)
+	ret = kvm_vcpu_map(&svm->vcpu, gpa_to_gfn(svm->vmcb->save.rax), &map);
+	if (ret) {
+		if (ret == -EINVAL)
+			kvm_inject_gp(&svm->vcpu, 0);
 		return 1;
+	}
+
+	nested_vmcb = map.hva;
 
 	svm->next_rip = kvm_rip_read(&svm->vcpu) + 3;
 	ret = kvm_skip_emulated_instruction(&svm->vcpu);
 
 	nested_svm_vmloadsave(svm->vmcb, nested_vmcb);
-	nested_svm_unmap(page);
+	kvm_vcpu_unmap(&svm->vcpu, &map, true);
 
 	return ret;
 }
@@ -6219,7 +6215,7 @@ static int svm_pre_leave_smm(struct kvm_vcpu *vcpu, u64 smbase)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 	struct vmcb *nested_vmcb;
-	struct page *page;
+	struct kvm_host_map map;
 	struct {
 		u64 guest;
 		u64 vmcb;
@@ -6233,11 +6229,16 @@ static int svm_pre_leave_smm(struct kvm_vcpu *vcpu, u64 smbase)
 
 	if (svm_state_save.guest) {
 		vcpu->arch.hflags &= ~HF_SMM_MASK;
-		nested_vmcb = nested_svm_map(svm, svm_state_save.vmcb, &page);
+		if (kvm_vcpu_map(&svm->vcpu, gpa_to_gfn(svm_state_save.vmcb), &map) == -EINVAL)
+			kvm_inject_gp(&svm->vcpu, 0);
+
+		nested_vmcb = map.hva;
+
 		if (nested_vmcb)
-			enter_svm_guest_mode(svm, svm_state_save.vmcb, nested_vmcb, page);
+			enter_svm_guest_mode(svm, svm_state_save.vmcb, nested_vmcb, &map);
 		else
 			ret = 1;
+
 		vcpu->arch.hflags |= HF_SMM_MASK;
 	}
 	return ret;
-- 
2.7.4

[PATCH v6 11/14] KVM/nVMX: Use kvm_vcpu_map for accessing the shadow VMCS

[KarimAllah Ahmed]

Use kvm_vcpu_map for accessing the shadow VMCS since using
kvm_vcpu_gpa_to_page() and kmap() will only work for guest memory that has
a "struct page".

Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
Reviewed-by: Konrad Rzessutek Wilk <konrad.wilk@oracle.com>
---
v4 -> v5:
- unmap with dirty flag
---
 arch/x86/kvm/vmx/nested.c | 25 ++++++++++++-------------
 1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 53b1063..3c173b9 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -588,20 +588,20 @@ static inline bool nested_vmx_prepare_msr_bitmap(struct kvm_vcpu *vcpu,
 static void nested_cache_shadow_vmcs12(struct kvm_vcpu *vcpu,
 				       struct vmcs12 *vmcs12)
 {
+	struct kvm_host_map map;
 	struct vmcs12 *shadow;
-	struct page *page;
 
 	if (!nested_cpu_has_shadow_vmcs(vmcs12) ||
 	    vmcs12->vmcs_link_pointer == -1ull)
 		return;
 
 	shadow = get_shadow_vmcs12(vcpu);
-	page = kvm_vcpu_gpa_to_page(vcpu, vmcs12->vmcs_link_pointer);
 
-	memcpy(shadow, kmap(page), VMCS12_SIZE);
+	if (kvm_vcpu_map(vcpu, gpa_to_gfn(vmcs12->vmcs_link_pointer), &map))
+		return;
 
-	kunmap(page);
-	kvm_release_page_clean(page);
+	memcpy(shadow, map.hva, VMCS12_SIZE);
+	kvm_vcpu_unmap(vcpu, &map, false);
 }
 
 static void nested_flush_cached_shadow_vmcs12(struct kvm_vcpu *vcpu,
@@ -2637,9 +2637,9 @@ static int nested_vmx_check_vmentry_prereqs(struct kvm_vcpu *vcpu,
 static int nested_vmx_check_vmcs_link_ptr(struct kvm_vcpu *vcpu,
 					  struct vmcs12 *vmcs12)
 {
-	int r;
-	struct page *page;
+	int r = 0;
 	struct vmcs12 *shadow;
+	struct kvm_host_map map;
 
 	if (vmcs12->vmcs_link_pointer == -1ull)
 		return 0;
@@ -2647,17 +2647,16 @@ static int nested_vmx_check_vmcs_link_ptr(struct kvm_vcpu *vcpu,
 	if (!page_address_valid(vcpu, vmcs12->vmcs_link_pointer))
 		return -EINVAL;
 
-	page = kvm_vcpu_gpa_to_page(vcpu, vmcs12->vmcs_link_pointer);
-	if (is_error_page(page))
+	if (kvm_vcpu_map(vcpu, gpa_to_gfn(vmcs12->vmcs_link_pointer), &map))
 		return -EINVAL;
 
-	r = 0;
-	shadow = kmap(page);
+	shadow = map.hva;
+
 	if (shadow->hdr.revision_id != VMCS12_REVISION ||
 	    shadow->hdr.shadow_vmcs != nested_cpu_has_shadow_vmcs(vmcs12))
 		r = -EINVAL;
-	kunmap(page);
-	kvm_release_page_clean(page);
+
+	kvm_vcpu_unmap(vcpu, &map, false);
 	return r;
 }
 
-- 
2.7.4

[PATCH v6 12/14] KVM/nVMX: Use kvm_vcpu_map for accessing the enlightened VMCS

[KarimAllah Ahmed]

Use kvm_vcpu_map for accessing the enlightened VMCS since using
kvm_vcpu_gpa_to_page() and kmap() will only work for guest memory that has
a "struct page".

Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
v4 -> v5:
- s/enhanced/enlightened
- unmap with dirty flag
---
 arch/x86/kvm/vmx/nested.c | 14 +++++---------
 arch/x86/kvm/vmx/vmx.h    |  2 +-
 2 files changed, 6 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 3c173b9..60ba582 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -193,10 +193,8 @@ static inline void nested_release_evmcs(struct kvm_vcpu *vcpu)
 	if (!vmx->nested.hv_evmcs)
 		return;
 
-	kunmap(vmx->nested.hv_evmcs_page);
-	kvm_release_page_dirty(vmx->nested.hv_evmcs_page);
+	kvm_vcpu_unmap(vcpu, &vmx->nested.hv_evmcs_map, true);
 	vmx->nested.hv_evmcs_vmptr = -1ull;
-	vmx->nested.hv_evmcs_page = NULL;
 	vmx->nested.hv_evmcs = NULL;
 }
 
@@ -1769,13 +1767,11 @@ static int nested_vmx_handle_enlightened_vmptrld(struct kvm_vcpu *vcpu,
 
 		nested_release_evmcs(vcpu);
 
-		vmx->nested.hv_evmcs_page = kvm_vcpu_gpa_to_page(
-			vcpu, assist_page.current_nested_vmcs);
-
-		if (unlikely(is_error_page(vmx->nested.hv_evmcs_page)))
+		if (kvm_vcpu_map(vcpu, gpa_to_gfn(assist_page.current_nested_vmcs),
+				 &vmx->nested.hv_evmcs_map))
 			return 0;
 
-		vmx->nested.hv_evmcs = kmap(vmx->nested.hv_evmcs_page);
+		vmx->nested.hv_evmcs = vmx->nested.hv_evmcs_map.hva;
 
 		/*
 		 * Currently, KVM only supports eVMCS version 1
@@ -4278,7 +4274,7 @@ static int handle_vmclear(struct kvm_vcpu *vcpu)
 		return nested_vmx_failValid(vcpu,
 			VMXERR_VMCLEAR_VMXON_POINTER);
 
-	if (vmx->nested.hv_evmcs_page) {
+	if (vmx->nested.hv_evmcs_map.hva) {
 		if (vmptr == vmx->nested.hv_evmcs_vmptr)
 			nested_release_evmcs(vcpu);
 	} else {
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index bd04725..a130139 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -172,7 +172,7 @@ struct nested_vmx {
 	} smm;
 
 	gpa_t hv_evmcs_vmptr;
-	struct page *hv_evmcs_page;
+	struct kvm_host_map hv_evmcs_map;
 	struct hv_enlightened_vmcs *hv_evmcs;
 };
 
-- 
2.7.4

[PATCH v6 13/14] KVM/nVMX: Use page_address_valid in a few more locations

[KarimAllah Ahmed]

Use page_address_valid in a few more locations that is already checking for
a page aligned address that does not cross the maximum physical address.

Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
---
 arch/x86/kvm/vmx/nested.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 60ba582..91e42f9 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -4203,7 +4203,7 @@ static int handle_vmon(struct kvm_vcpu *vcpu)
 	 * Note - IA32_VMX_BASIC[48] will never be 1 for the nested case;
 	 * which replaces physical address width with 32
 	 */
-	if (!PAGE_ALIGNED(vmptr) || (vmptr >> cpuid_maxphyaddr(vcpu)))
+	if (!page_address_valid(vcpu, vmptr))
 		return nested_vmx_failInvalid(vcpu);
 
 	if (kvm_read_guest(vcpu->kvm, vmptr, &revision, sizeof(revision)) ||
@@ -4266,7 +4266,7 @@ static int handle_vmclear(struct kvm_vcpu *vcpu)
 	if (nested_vmx_get_vmptr(vcpu, &vmptr))
 		return 1;
 
-	if (!PAGE_ALIGNED(vmptr) || (vmptr >> cpuid_maxphyaddr(vcpu)))
+	if (!page_address_valid(vcpu, vmptr))
 		return nested_vmx_failValid(vcpu,
 			VMXERR_VMCLEAR_INVALID_ADDRESS);
 
@@ -4473,7 +4473,7 @@ static int handle_vmptrld(struct kvm_vcpu *vcpu)
 	if (nested_vmx_get_vmptr(vcpu, &vmptr))
 		return 1;
 
-	if (!PAGE_ALIGNED(vmptr) || (vmptr >> cpuid_maxphyaddr(vcpu)))
+	if (!page_address_valid(vcpu, vmptr))
 		return nested_vmx_failValid(vcpu,
 			VMXERR_VMPTRLD_INVALID_ADDRESS);
 
-- 
2.7.4

[PATCH v6 14/14] kvm, x86: Properly check whether a pfn is an MMIO or not

[KarimAllah Ahmed]

pfn_valid check is not sufficient because it only checks if a page has a struct
page or not, if "mem=" was passed to the kernel some valid pages won't have a
struct page. This means that if guests were assigned valid memory that lies
after the mem= boundary it will be passed uncached to the guest no matter what
the guest caching attributes are for this memory.

Introduce a new function e820__mapped_raw_any which is equivalent to
e820__mapped_any but uses the original e820 unmodified and use it to
identify real *RAM*.

Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
---
v1 -> v2:
- Introduce e820__mapped_raw_any
---
 arch/x86/include/asm/e820/api.h |  1 +
 arch/x86/kernel/e820.c          | 18 +++++++++++++++---
 arch/x86/kvm/mmu.c              |  5 ++++-
 3 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/e820/api.h b/arch/x86/include/asm/e820/api.h
index 4562062..b3f6e89 100644
--- a/arch/x86/include/asm/e820/api.h
+++ b/arch/x86/include/asm/e820/api.h
@@ -12,6 +12,7 @@ extern unsigned long e820_saved_max_low_pfn;
 
 extern unsigned long pci_mem_start;
 
+extern bool e820__mapped_raw_any(u64 start, u64 end, enum e820_type type);
 extern bool e820__mapped_any(u64 start, u64 end, enum e820_type type);
 extern bool e820__mapped_all(u64 start, u64 end, enum e820_type type);
 
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index ef914d0..3039659 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -75,12 +75,13 @@ EXPORT_SYMBOL(pci_mem_start);
  * This function checks if any part of the range <start,end> is mapped
  * with type.
  */
-bool e820__mapped_any(u64 start, u64 end, enum e820_type type)
+static bool _e820__mapped_any(struct e820_table *table,
+			      u64 start, u64 end, enum e820_type type)
 {
 	int i;
 
-	for (i = 0; i < e820_table->nr_entries; i++) {
-		struct e820_entry *entry = &e820_table->entries[i];
+	for (i = 0; i < table->nr_entries; i++) {
+		struct e820_entry *entry = &table->entries[i];
 
 		if (type && entry->type != type)
 			continue;
@@ -90,6 +91,17 @@ bool e820__mapped_any(u64 start, u64 end, enum e820_type type)
 	}
 	return 0;
 }
+
+bool e820__mapped_raw_any(u64 start, u64 end, enum e820_type type)
+{
+	return _e820__mapped_any(e820_table_firmware, start, end, type);
+}
+EXPORT_SYMBOL_GPL(e820__mapped_raw_any);
+
+bool e820__mapped_any(u64 start, u64 end, enum e820_type type)
+{
+	return _e820__mapped_any(e820_table, start, end, type);
+}
 EXPORT_SYMBOL_GPL(e820__mapped_any);
 
 /*
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index da9c423..abf6a0d 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -44,6 +44,7 @@
 #include <asm/page.h>
 #include <asm/pat.h>
 #include <asm/cmpxchg.h>
+#include <asm/e820/api.h>
 #include <asm/io.h>
 #include <asm/vmx.h>
 #include <asm/kvm_page_track.h>
@@ -2875,7 +2876,9 @@ static bool kvm_is_mmio_pfn(kvm_pfn_t pfn)
 			 */
 			(!pat_enabled() || pat_pfn_immune_to_uc_mtrr(pfn));
 
-	return true;
+	return !e820__mapped_raw_any(pfn_to_hpa(pfn),
+				     pfn_to_hpa(pfn + 1) - 1,
+				     E820_TYPE_RAM);
 }
 
 /* Bits which may be returned by set_spte() */
-- 
2.7.4

Re: [PATCH v6 00/14] KVM/X86: Introduce a new guest mapping interface

[Raslan, KarimAllah]

I guess this patch series missed the 5.1 merge window? :)

On Thu, 2019-01-31 at 21:24 +0100, KarimAllah Ahmed wrote:
> Guest memory can either be directly managed by the kernel (i.e. have a "struct
> page") or they can simply live outside kernel control (i.e. do not have a
> "struct page"). KVM mostly support these two modes, except in a few places
> where the code seems to assume that guest memory must have a "struct page".
> 
> This patchset introduces a new mapping interface to map guest memory into host
> kernel memory which also supports PFN-based memory (i.e. memory without 'struct
> page'). It also converts all offending code to this interface or simply
> read/write directly from guest memory. Patch 2 is additionally fixing an
> incorrect page release and marking the page as dirty (i.e. as a side-effect of
> using the helper function to write).
> 
> As far as I can see all offending code is now fixed except the APIC-access page
> which I will handle in a seperate series along with dropping
> kvm_vcpu_gfn_to_page and kvm_vcpu_gpa_to_page from the internal KVM API.
> 
> The current implementation of the new API uses memremap to map memory that does
> not have a "struct page". This proves to be very slow for high frequency
> mappings. Since this does not affect the normal use-case where a "struct page"
> is available, the performance of this API will be handled by a seperate patch
> series.
> 
> So the simple way to use memory outside kernel control is:
> 
> 1- Pass 'mem=' in the kernel command-line to limit the amount of memory managed 
>    by the kernel.
> 2- Map this physical memory you want to give to the guest with:
>    mmap("/dev/mem", physical_address_offset, ..)
> 3- Use the user-space virtual address as the "userspace_addr" field in
>    KVM_SET_USER_MEMORY_REGION ioctl.
> 
> v5 -> v6:
> - Added one extra patch to ensure that support for this mem= case is complete
>   for x86.
> - Added a helper function to check if the mapping is mapped or not.
> - Added more comments on the struct.
> - Setting ->page to NULL on unmap and to a poison ptr if unused during map
> - Checking for map ptr before using it.
> - Change kvm_vcpu_unmap to also mark page dirty for LM. That requires
>   passing the vCPU pointer again to this function.
> 
> v4 -> v5:
> - Introduce a new parameter 'dirty' into kvm_vcpu_unmap
> - A horrible rebase due to nested.c :)
> - Dropped a couple of hyperv patches as the code was fixed already as a
>   side-effect of another patch.
> - Added a new trivial cleanup patch.
> 
> v3 -> v4:
> - Rebase
> - Add a new patch to also fix the newly introduced enlightned VMCS.
> 
> v2 -> v3:
> - Rebase
> - Add a new patch to also fix the newly introduced shadow VMCS.
> 
> Filippo Sironi (1):
>   X86/KVM: Handle PFNs outside of kernel reach when touching GPTEs
> 
> KarimAllah Ahmed (13):
>   X86/nVMX: handle_vmon: Read 4 bytes from guest memory
>   X86/nVMX: Update the PML table without mapping and unmapping the page
>   KVM: Introduce a new guest mapping API
>   X86/nVMX: handle_vmptrld: Use kvm_vcpu_map when copying VMCS12 from
>     guest memory
>   KVM/nVMX: Use kvm_vcpu_map when mapping the L1 MSR bitmap
>   KVM/nVMX: Use kvm_vcpu_map when mapping the virtual APIC page
>   KVM/nVMX: Use kvm_vcpu_map when mapping the posted interrupt
>     descriptor table
>   KVM/X86: Use kvm_vcpu_map in emulator_cmpxchg_emulated
>   KVM/nSVM: Use the new mapping API for mapping guest memory
>   KVM/nVMX: Use kvm_vcpu_map for accessing the shadow VMCS
>   KVM/nVMX: Use kvm_vcpu_map for accessing the enlightened VMCS
>   KVM/nVMX: Use page_address_valid in a few more locations
>   kvm, x86: Properly check whether a pfn is an MMIO or not
> 
>  arch/x86/include/asm/e820/api.h |   1 +
>  arch/x86/kernel/e820.c          |  18 ++++-
>  arch/x86/kvm/mmu.c              |   5 +-
>  arch/x86/kvm/paging_tmpl.h      |  38 +++++++---
>  arch/x86/kvm/svm.c              |  97 ++++++++++++------------
>  arch/x86/kvm/vmx/nested.c       | 160 +++++++++++++++-------------------------
>  arch/x86/kvm/vmx/vmx.c          |  19 ++---
>  arch/x86/kvm/vmx/vmx.h          |   9 ++-
>  arch/x86/kvm/x86.c              |  14 ++--
>  include/linux/kvm_host.h        |  28 +++++++
>  virt/kvm/kvm_main.c             |  64 ++++++++++++++++
>  11 files changed, 267 insertions(+), 186 deletions(-)
> 



Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrer: Christian Schlaeger, Ralf Herbrich
Ust-ID: DE 289 237 879
Eingetragen am Amtsgericht Charlottenburg HRB 149173 B

Re: [PATCH v6 00/14] KVM/X86: Introduce a new guest mapping interface

[Konrad Rzeszutek Wilk]

On Mon, Mar 18, 2019 at 01:10:24PM +0000, Raslan, KarimAllah wrote:
> I guess this patch series missed the 5.1 merge window? :)

Were there any outstanding fixes that had to be addressed?

> 
> On Thu, 2019-01-31 at 21:24 +0100, KarimAllah Ahmed wrote:
> > Guest memory can either be directly managed by the kernel (i.e. have a "struct
> > page") or they can simply live outside kernel control (i.e. do not have a
> > "struct page"). KVM mostly support these two modes, except in a few places
> > where the code seems to assume that guest memory must have a "struct page".
> > 
> > This patchset introduces a new mapping interface to map guest memory into host
> > kernel memory which also supports PFN-based memory (i.e. memory without 'struct
> > page'). It also converts all offending code to this interface or simply
> > read/write directly from guest memory. Patch 2 is additionally fixing an
> > incorrect page release and marking the page as dirty (i.e. as a side-effect of
> > using the helper function to write).
> > 
> > As far as I can see all offending code is now fixed except the APIC-access page
> > which I will handle in a seperate series along with dropping
> > kvm_vcpu_gfn_to_page and kvm_vcpu_gpa_to_page from the internal KVM API.
> > 
> > The current implementation of the new API uses memremap to map memory that does
> > not have a "struct page". This proves to be very slow for high frequency
> > mappings. Since this does not affect the normal use-case where a "struct page"
> > is available, the performance of this API will be handled by a seperate patch
> > series.
> > 
> > So the simple way to use memory outside kernel control is:
> > 
> > 1- Pass 'mem=' in the kernel command-line to limit the amount of memory managed 
> >    by the kernel.
> > 2- Map this physical memory you want to give to the guest with:
> >    mmap("/dev/mem", physical_address_offset, ..)
> > 3- Use the user-space virtual address as the "userspace_addr" field in
> >    KVM_SET_USER_MEMORY_REGION ioctl.
> > 
> > v5 -> v6:
> > - Added one extra patch to ensure that support for this mem= case is complete
> >   for x86.
> > - Added a helper function to check if the mapping is mapped or not.
> > - Added more comments on the struct.
> > - Setting ->page to NULL on unmap and to a poison ptr if unused during map
> > - Checking for map ptr before using it.
> > - Change kvm_vcpu_unmap to also mark page dirty for LM. That requires
> >   passing the vCPU pointer again to this function.
> > 
> > v4 -> v5:
> > - Introduce a new parameter 'dirty' into kvm_vcpu_unmap
> > - A horrible rebase due to nested.c :)
> > - Dropped a couple of hyperv patches as the code was fixed already as a
> >   side-effect of another patch.
> > - Added a new trivial cleanup patch.
> > 
> > v3 -> v4:
> > - Rebase
> > - Add a new patch to also fix the newly introduced enlightned VMCS.
> > 
> > v2 -> v3:
> > - Rebase
> > - Add a new patch to also fix the newly introduced shadow VMCS.
> > 
> > Filippo Sironi (1):
> >   X86/KVM: Handle PFNs outside of kernel reach when touching GPTEs
> > 
> > KarimAllah Ahmed (13):
> >   X86/nVMX: handle_vmon: Read 4 bytes from guest memory
> >   X86/nVMX: Update the PML table without mapping and unmapping the page
> >   KVM: Introduce a new guest mapping API
> >   X86/nVMX: handle_vmptrld: Use kvm_vcpu_map when copying VMCS12 from
> >     guest memory
> >   KVM/nVMX: Use kvm_vcpu_map when mapping the L1 MSR bitmap
> >   KVM/nVMX: Use kvm_vcpu_map when mapping the virtual APIC page
> >   KVM/nVMX: Use kvm_vcpu_map when mapping the posted interrupt
> >     descriptor table
> >   KVM/X86: Use kvm_vcpu_map in emulator_cmpxchg_emulated
> >   KVM/nSVM: Use the new mapping API for mapping guest memory
> >   KVM/nVMX: Use kvm_vcpu_map for accessing the shadow VMCS
> >   KVM/nVMX: Use kvm_vcpu_map for accessing the enlightened VMCS
> >   KVM/nVMX: Use page_address_valid in a few more locations
> >   kvm, x86: Properly check whether a pfn is an MMIO or not
> > 
> >  arch/x86/include/asm/e820/api.h |   1 +
> >  arch/x86/kernel/e820.c          |  18 ++++-
> >  arch/x86/kvm/mmu.c              |   5 +-
> >  arch/x86/kvm/paging_tmpl.h      |  38 +++++++---
> >  arch/x86/kvm/svm.c              |  97 ++++++++++++------------
> >  arch/x86/kvm/vmx/nested.c       | 160 +++++++++++++++-------------------------
> >  arch/x86/kvm/vmx/vmx.c          |  19 ++---
> >  arch/x86/kvm/vmx/vmx.h          |   9 ++-
> >  arch/x86/kvm/x86.c              |  14 ++--
> >  include/linux/kvm_host.h        |  28 +++++++
> >  virt/kvm/kvm_main.c             |  64 ++++++++++++++++
> >  11 files changed, 267 insertions(+), 186 deletions(-)
> > 
> 
> 
> 
> Amazon Development Center Germany GmbH
> Krausenstr. 38
> 10117 Berlin
> Geschaeftsfuehrer: Christian Schlaeger, Ralf Herbrich
> Ust-ID: DE 289 237 879
> Eingetragen am Amtsgericht Charlottenburg HRB 149173 B
> 

Re: [PATCH v6 00/14] KVM/X86: Introduce a new guest mapping interface

[Raslan, KarimAllah]

On Mon, 2019-03-18 at 10:22 -0400, Konrad Rzeszutek Wilk wrote:
> On Mon, Mar 18, 2019 at 01:10:24PM +0000, Raslan, KarimAllah wrote:
> > 
> > I guess this patch series missed the 5.1 merge window? :)
> 
> Were there any outstanding fixes that had to be addressed?

Not as far as I can remember. This version addressed all requests raised in 
'v5'.

> 
> > 
> > 
> > On Thu, 2019-01-31 at 21:24 +0100, KarimAllah Ahmed wrote:
> > > 
> > > Guest memory can either be directly managed by the kernel (i.e. have a "struct
> > > page") or they can simply live outside kernel control (i.e. do not have a
> > > "struct page"). KVM mostly support these two modes, except in a few places
> > > where the code seems to assume that guest memory must have a "struct page".
> > > 
> > > This patchset introduces a new mapping interface to map guest memory into host
> > > kernel memory which also supports PFN-based memory (i.e. memory without 'struct
> > > page'). It also converts all offending code to this interface or simply
> > > read/write directly from guest memory. Patch 2 is additionally fixing an
> > > incorrect page release and marking the page as dirty (i.e. as a side-effect of
> > > using the helper function to write).
> > > 
> > > As far as I can see all offending code is now fixed except the APIC-access page
> > > which I will handle in a seperate series along with dropping
> > > kvm_vcpu_gfn_to_page and kvm_vcpu_gpa_to_page from the internal KVM API.
> > > 
> > > The current implementation of the new API uses memremap to map memory that does
> > > not have a "struct page". This proves to be very slow for high frequency
> > > mappings. Since this does not affect the normal use-case where a "struct page"
> > > is available, the performance of this API will be handled by a seperate patch
> > > series.
> > > 
> > > So the simple way to use memory outside kernel control is:
> > > 
> > > 1- Pass 'mem=' in the kernel command-line to limit the amount of memory managed 
> > >    by the kernel.
> > > 2- Map this physical memory you want to give to the guest with:
> > >    mmap("/dev/mem", physical_address_offset, ..)
> > > 3- Use the user-space virtual address as the "userspace_addr" field in
> > >    KVM_SET_USER_MEMORY_REGION ioctl.
> > > 
> > > v5 -> v6:
> > > - Added one extra patch to ensure that support for this mem= case is complete
> > >   for x86.
> > > - Added a helper function to check if the mapping is mapped or not.
> > > - Added more comments on the struct.
> > > - Setting ->page to NULL on unmap and to a poison ptr if unused during map
> > > - Checking for map ptr before using it.
> > > - Change kvm_vcpu_unmap to also mark page dirty for LM. That requires
> > >   passing the vCPU pointer again to this function.
> > > 
> > > v4 -> v5:
> > > - Introduce a new parameter 'dirty' into kvm_vcpu_unmap
> > > - A horrible rebase due to nested.c :)
> > > - Dropped a couple of hyperv patches as the code was fixed already as a
> > >   side-effect of another patch.
> > > - Added a new trivial cleanup patch.
> > > 
> > > v3 -> v4:
> > > - Rebase
> > > - Add a new patch to also fix the newly introduced enlightned VMCS.
> > > 
> > > v2 -> v3:
> > > - Rebase
> > > - Add a new patch to also fix the newly introduced shadow VMCS.
> > > 
> > > Filippo Sironi (1):
> > >   X86/KVM: Handle PFNs outside of kernel reach when touching GPTEs
> > > 
> > > KarimAllah Ahmed (13):
> > >   X86/nVMX: handle_vmon: Read 4 bytes from guest memory
> > >   X86/nVMX: Update the PML table without mapping and unmapping the page
> > >   KVM: Introduce a new guest mapping API
> > >   X86/nVMX: handle_vmptrld: Use kvm_vcpu_map when copying VMCS12 from
> > >     guest memory
> > >   KVM/nVMX: Use kvm_vcpu_map when mapping the L1 MSR bitmap
> > >   KVM/nVMX: Use kvm_vcpu_map when mapping the virtual APIC page
> > >   KVM/nVMX: Use kvm_vcpu_map when mapping the posted interrupt
> > >     descriptor table
> > >   KVM/X86: Use kvm_vcpu_map in emulator_cmpxchg_emulated
> > >   KVM/nSVM: Use the new mapping API for mapping guest memory
> > >   KVM/nVMX: Use kvm_vcpu_map for accessing the shadow VMCS
> > >   KVM/nVMX: Use kvm_vcpu_map for accessing the enlightened VMCS
> > >   KVM/nVMX: Use page_address_valid in a few more locations
> > >   kvm, x86: Properly check whether a pfn is an MMIO or not
> > > 
> > >  arch/x86/include/asm/e820/api.h |   1 +
> > >  arch/x86/kernel/e820.c          |  18 ++++-
> > >  arch/x86/kvm/mmu.c              |   5 +-
> > >  arch/x86/kvm/paging_tmpl.h      |  38 +++++++---
> > >  arch/x86/kvm/svm.c              |  97 ++++++++++++------------
> > >  arch/x86/kvm/vmx/nested.c       | 160 +++++++++++++++-------------------------
> > >  arch/x86/kvm/vmx/vmx.c          |  19 ++---
> > >  arch/x86/kvm/vmx/vmx.h          |   9 ++-
> > >  arch/x86/kvm/x86.c              |  14 ++--
> > >  include/linux/kvm_host.h        |  28 +++++++
> > >  virt/kvm/kvm_main.c             |  64 ++++++++++++++++
> > >  11 files changed, 267 insertions(+), 186 deletions(-)
> > > 
> > 
> > 
> > 
> > Amazon Development Center Germany GmbH
> > Krausenstr. 38
> > 10117 Berlin
> > Geschaeftsfuehrer: Christian Schlaeger, Ralf Herbrich
> > Ust-ID: DE 289 237 879
> > Eingetragen am Amtsgericht Charlottenburg HRB 149173 B
> > 



Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrer: Christian Schlaeger, Ralf Herbrich
Ust-ID: DE 289 237 879
Eingetragen am Amtsgericht Charlottenburg HRB 149173 B

Re: [PATCH v6 00/14] KVM/X86: Introduce a new guest mapping interface

[Konrad Rzeszutek Wilk]

On Mon, Mar 18, 2019 at 07:16:28PM +0000, Raslan, KarimAllah wrote:
> On Mon, 2019-03-18 at 10:22 -0400, Konrad Rzeszutek Wilk wrote:
> > On Mon, Mar 18, 2019 at 01:10:24PM +0000, Raslan, KarimAllah wrote:
> > > 
> > > I guess this patch series missed the 5.1 merge window? :)
> > 
> > Were there any outstanding fixes that had to be addressed?
> 
> Not as far as I can remember. This version addressed all requests raised in 
> 'v5'.

Paolo,

Are there any concerns in pulling this patchset in?

Thank you!
> 
> > 
> > > 
> > > 
> > > On Thu, 2019-01-31 at 21:24 +0100, KarimAllah Ahmed wrote:
> > > > 
> > > > Guest memory can either be directly managed by the kernel (i.e. have a "struct
> > > > page") or they can simply live outside kernel control (i.e. do not have a
> > > > "struct page"). KVM mostly support these two modes, except in a few places
> > > > where the code seems to assume that guest memory must have a "struct page".
> > > > 
> > > > This patchset introduces a new mapping interface to map guest memory into host
> > > > kernel memory which also supports PFN-based memory (i.e. memory without 'struct
> > > > page'). It also converts all offending code to this interface or simply
> > > > read/write directly from guest memory. Patch 2 is additionally fixing an
> > > > incorrect page release and marking the page as dirty (i.e. as a side-effect of
> > > > using the helper function to write).
> > > > 
> > > > As far as I can see all offending code is now fixed except the APIC-access page
> > > > which I will handle in a seperate series along with dropping
> > > > kvm_vcpu_gfn_to_page and kvm_vcpu_gpa_to_page from the internal KVM API.
> > > > 
> > > > The current implementation of the new API uses memremap to map memory that does
> > > > not have a "struct page". This proves to be very slow for high frequency
> > > > mappings. Since this does not affect the normal use-case where a "struct page"
> > > > is available, the performance of this API will be handled by a seperate patch
> > > > series.
> > > > 
> > > > So the simple way to use memory outside kernel control is:
> > > > 
> > > > 1- Pass 'mem=' in the kernel command-line to limit the amount of memory managed 
> > > >    by the kernel.
> > > > 2- Map this physical memory you want to give to the guest with:
> > > >    mmap("/dev/mem", physical_address_offset, ..)
> > > > 3- Use the user-space virtual address as the "userspace_addr" field in
> > > >    KVM_SET_USER_MEMORY_REGION ioctl.
> > > > 
> > > > v5 -> v6:
> > > > - Added one extra patch to ensure that support for this mem= case is complete
> > > >   for x86.
> > > > - Added a helper function to check if the mapping is mapped or not.
> > > > - Added more comments on the struct.
> > > > - Setting ->page to NULL on unmap and to a poison ptr if unused during map
> > > > - Checking for map ptr before using it.
> > > > - Change kvm_vcpu_unmap to also mark page dirty for LM. That requires
> > > >   passing the vCPU pointer again to this function.
> > > > 
> > > > v4 -> v5:
> > > > - Introduce a new parameter 'dirty' into kvm_vcpu_unmap
> > > > - A horrible rebase due to nested.c :)
> > > > - Dropped a couple of hyperv patches as the code was fixed already as a
> > > >   side-effect of another patch.
> > > > - Added a new trivial cleanup patch.
> > > > 
> > > > v3 -> v4:
> > > > - Rebase
> > > > - Add a new patch to also fix the newly introduced enlightned VMCS.
> > > > 
> > > > v2 -> v3:
> > > > - Rebase
> > > > - Add a new patch to also fix the newly introduced shadow VMCS.
> > > > 
> > > > Filippo Sironi (1):
> > > >   X86/KVM: Handle PFNs outside of kernel reach when touching GPTEs
> > > > 
> > > > KarimAllah Ahmed (13):
> > > >   X86/nVMX: handle_vmon: Read 4 bytes from guest memory
> > > >   X86/nVMX: Update the PML table without mapping and unmapping the page
> > > >   KVM: Introduce a new guest mapping API
> > > >   X86/nVMX: handle_vmptrld: Use kvm_vcpu_map when copying VMCS12 from
> > > >     guest memory
> > > >   KVM/nVMX: Use kvm_vcpu_map when mapping the L1 MSR bitmap
> > > >   KVM/nVMX: Use kvm_vcpu_map when mapping the virtual APIC page
> > > >   KVM/nVMX: Use kvm_vcpu_map when mapping the posted interrupt
> > > >     descriptor table
> > > >   KVM/X86: Use kvm_vcpu_map in emulator_cmpxchg_emulated
> > > >   KVM/nSVM: Use the new mapping API for mapping guest memory
> > > >   KVM/nVMX: Use kvm_vcpu_map for accessing the shadow VMCS
> > > >   KVM/nVMX: Use kvm_vcpu_map for accessing the enlightened VMCS
> > > >   KVM/nVMX: Use page_address_valid in a few more locations
> > > >   kvm, x86: Properly check whether a pfn is an MMIO or not
> > > > 
> > > >  arch/x86/include/asm/e820/api.h |   1 +
> > > >  arch/x86/kernel/e820.c          |  18 ++++-
> > > >  arch/x86/kvm/mmu.c              |   5 +-
> > > >  arch/x86/kvm/paging_tmpl.h      |  38 +++++++---
> > > >  arch/x86/kvm/svm.c              |  97 ++++++++++++------------
> > > >  arch/x86/kvm/vmx/nested.c       | 160 +++++++++++++++-------------------------
> > > >  arch/x86/kvm/vmx/vmx.c          |  19 ++---
> > > >  arch/x86/kvm/vmx/vmx.h          |   9 ++-
> > > >  arch/x86/kvm/x86.c              |  14 ++--
> > > >  include/linux/kvm_host.h        |  28 +++++++
> > > >  virt/kvm/kvm_main.c             |  64 ++++++++++++++++
> > > >  11 files changed, 267 insertions(+), 186 deletions(-)
> > > > 
> > > 
> > > 
> > > 
> > > Amazon Development Center Germany GmbH
> > > Krausenstr. 38
> > > 10117 Berlin
> > > Geschaeftsfuehrer: Christian Schlaeger, Ralf Herbrich
> > > Ust-ID: DE 289 237 879
> > > Eingetragen am Amtsgericht Charlottenburg HRB 149173 B
> > > 
> 
> 
> 
> Amazon Development Center Germany GmbH
> Krausenstr. 38
> 10117 Berlin
> Geschaeftsfuehrer: Christian Schlaeger, Ralf Herbrich
> Ust-ID: DE 289 237 879
> Eingetragen am Amtsgericht Charlottenburg HRB 149173 B
> 

Re: [PATCH v6 00/14] KVM/X86: Introduce a new guest mapping interface

[Paolo Bonzini]

On 29/04/19 15:58, Konrad Rzeszutek Wilk wrote:
> On Mon, Mar 18, 2019 at 07:16:28PM +0000, Raslan, KarimAllah wrote:
>> On Mon, 2019-03-18 at 10:22 -0400, Konrad Rzeszutek Wilk wrote:
>>> On Mon, Mar 18, 2019 at 01:10:24PM +0000, Raslan, KarimAllah wrote:
>>>>
>>>> I guess this patch series missed the 5.1 merge window? :)
>>>
>>> Were there any outstanding fixes that had to be addressed?
>>
>> Not as far as I can remember. This version addressed all requests raised in 
>> 'v5'.
> 
> Paolo,
> 
> Are there any concerns in pulling this patchset in?

No, it should be in 5.2.

Paolo

> 
> Thank you!
>>
>>>
>>>>
>>>>
>>>> On Thu, 2019-01-31 at 21:24 +0100, KarimAllah Ahmed wrote:
>>>>>
>>>>> Guest memory can either be directly managed by the kernel (i.e. have a "struct
>>>>> page") or they can simply live outside kernel control (i.e. do not have a
>>>>> "struct page"). KVM mostly support these two modes, except in a few places
>>>>> where the code seems to assume that guest memory must have a "struct page".
>>>>>
>>>>> This patchset introduces a new mapping interface to map guest memory into host
>>>>> kernel memory which also supports PFN-based memory (i.e. memory without 'struct
>>>>> page'). It also converts all offending code to this interface or simply
>>>>> read/write directly from guest memory. Patch 2 is additionally fixing an
>>>>> incorrect page release and marking the page as dirty (i.e. as a side-effect of
>>>>> using the helper function to write).
>>>>>
>>>>> As far as I can see all offending code is now fixed except the APIC-access page
>>>>> which I will handle in a seperate series along with dropping
>>>>> kvm_vcpu_gfn_to_page and kvm_vcpu_gpa_to_page from the internal KVM API.
>>>>>
>>>>> The current implementation of the new API uses memremap to map memory that does
>>>>> not have a "struct page". This proves to be very slow for high frequency
>>>>> mappings. Since this does not affect the normal use-case where a "struct page"
>>>>> is available, the performance of this API will be handled by a seperate patch
>>>>> series.
>>>>>
>>>>> So the simple way to use memory outside kernel control is:
>>>>>
>>>>> 1- Pass 'mem=' in the kernel command-line to limit the amount of memory managed 
>>>>>    by the kernel.
>>>>> 2- Map this physical memory you want to give to the guest with:
>>>>>    mmap("/dev/mem", physical_address_offset, ..)
>>>>> 3- Use the user-space virtual address as the "userspace_addr" field in
>>>>>    KVM_SET_USER_MEMORY_REGION ioctl.
>>>>>
>>>>> v5 -> v6:
>>>>> - Added one extra patch to ensure that support for this mem= case is complete
>>>>>   for x86.
>>>>> - Added a helper function to check if the mapping is mapped or not.
>>>>> - Added more comments on the struct.
>>>>> - Setting ->page to NULL on unmap and to a poison ptr if unused during map
>>>>> - Checking for map ptr before using it.
>>>>> - Change kvm_vcpu_unmap to also mark page dirty for LM. That requires
>>>>>   passing the vCPU pointer again to this function.
>>>>>
>>>>> v4 -> v5:
>>>>> - Introduce a new parameter 'dirty' into kvm_vcpu_unmap
>>>>> - A horrible rebase due to nested.c :)
>>>>> - Dropped a couple of hyperv patches as the code was fixed already as a
>>>>>   side-effect of another patch.
>>>>> - Added a new trivial cleanup patch.
>>>>>
>>>>> v3 -> v4:
>>>>> - Rebase
>>>>> - Add a new patch to also fix the newly introduced enlightned VMCS.
>>>>>
>>>>> v2 -> v3:
>>>>> - Rebase
>>>>> - Add a new patch to also fix the newly introduced shadow VMCS.
>>>>>
>>>>> Filippo Sironi (1):
>>>>>   X86/KVM: Handle PFNs outside of kernel reach when touching GPTEs
>>>>>
>>>>> KarimAllah Ahmed (13):
>>>>>   X86/nVMX: handle_vmon: Read 4 bytes from guest memory
>>>>>   X86/nVMX: Update the PML table without mapping and unmapping the page
>>>>>   KVM: Introduce a new guest mapping API
>>>>>   X86/nVMX: handle_vmptrld: Use kvm_vcpu_map when copying VMCS12 from
>>>>>     guest memory
>>>>>   KVM/nVMX: Use kvm_vcpu_map when mapping the L1 MSR bitmap
>>>>>   KVM/nVMX: Use kvm_vcpu_map when mapping the virtual APIC page
>>>>>   KVM/nVMX: Use kvm_vcpu_map when mapping the posted interrupt
>>>>>     descriptor table
>>>>>   KVM/X86: Use kvm_vcpu_map in emulator_cmpxchg_emulated
>>>>>   KVM/nSVM: Use the new mapping API for mapping guest memory
>>>>>   KVM/nVMX: Use kvm_vcpu_map for accessing the shadow VMCS
>>>>>   KVM/nVMX: Use kvm_vcpu_map for accessing the enlightened VMCS
>>>>>   KVM/nVMX: Use page_address_valid in a few more locations
>>>>>   kvm, x86: Properly check whether a pfn is an MMIO or not
>>>>>
>>>>>  arch/x86/include/asm/e820/api.h |   1 +
>>>>>  arch/x86/kernel/e820.c          |  18 ++++-
>>>>>  arch/x86/kvm/mmu.c              |   5 +-
>>>>>  arch/x86/kvm/paging_tmpl.h      |  38 +++++++---
>>>>>  arch/x86/kvm/svm.c              |  97 ++++++++++++------------
>>>>>  arch/x86/kvm/vmx/nested.c       | 160 +++++++++++++++-------------------------
>>>>>  arch/x86/kvm/vmx/vmx.c          |  19 ++---
>>>>>  arch/x86/kvm/vmx/vmx.h          |   9 ++-
>>>>>  arch/x86/kvm/x86.c              |  14 ++--
>>>>>  include/linux/kvm_host.h        |  28 +++++++
>>>>>  virt/kvm/kvm_main.c             |  64 ++++++++++++++++
>>>>>  11 files changed, 267 insertions(+), 186 deletions(-)
>>>>>
>>>>
>>>>
>>>>
>>>> Amazon Development Center Germany GmbH
>>>> Krausenstr. 38
>>>> 10117 Berlin
>>>> Geschaeftsfuehrer: Christian Schlaeger, Ralf Herbrich
>>>> Ust-ID: DE 289 237 879
>>>> Eingetragen am Amtsgericht Charlottenburg HRB 149173 B
>>>>
>>
>>
>>
>> Amazon Development Center Germany GmbH
>> Krausenstr. 38
>> 10117 Berlin
>> Geschaeftsfuehrer: Christian Schlaeger, Ralf Herbrich
>> Ust-ID: DE 289 237 879
>> Eingetragen am Amtsgericht Charlottenburg HRB 149173 B
>>

Re: [PATCH v6 08/14] KVM/nVMX: Use kvm_vcpu_map when mapping the posted interrupt descriptor table

[Jim Mattson]

On Thu, Jan 31, 2019 at 12:28 PM KarimAllah Ahmed <karahmed@amazon.de> wrote:
>
> Use kvm_vcpu_map when mapping the posted interrupt descriptor table since
> using kvm_vcpu_gpa_to_page() and kmap() will only work for guest memory
> that has a "struct page".
>
> One additional semantic change is that the virtual host mapping lifecycle
> has changed a bit. It now has the same lifetime of the pinning of the
> interrupt descriptor table page on the host side.
>
> Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> ---
> v4 -> v5:
> - unmap with dirty flag
>
> v1 -> v2:
> - Do not change the lifecycle of the mapping (pbonzini)
> ---
>  arch/x86/kvm/vmx/nested.c | 43 ++++++++++++-------------------------------
>  arch/x86/kvm/vmx/vmx.h    |  2 +-
>  2 files changed, 13 insertions(+), 32 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index 31b352c..53b1063 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -230,12 +230,8 @@ static void free_nested(struct kvm_vcpu *vcpu)
>                 vmx->nested.apic_access_page = NULL;
>         }
>         kvm_vcpu_unmap(vcpu, &vmx->nested.virtual_apic_map, true);
> -       if (vmx->nested.pi_desc_page) {
> -               kunmap(vmx->nested.pi_desc_page);
> -               kvm_release_page_dirty(vmx->nested.pi_desc_page);
> -               vmx->nested.pi_desc_page = NULL;
> -               vmx->nested.pi_desc = NULL;
> -       }
> +       kvm_vcpu_unmap(vcpu, &vmx->nested.pi_desc_map, true);
> +       vmx->nested.pi_desc = NULL;
>
>         kvm_mmu_free_roots(vcpu, &vcpu->arch.guest_mmu, KVM_MMU_ROOTS_ALL);
>
> @@ -2868,26 +2864,15 @@ static void nested_get_vmcs12_pages(struct kvm_vcpu *vcpu)
>         }
>
>         if (nested_cpu_has_posted_intr(vmcs12)) {
> -               if (vmx->nested.pi_desc_page) { /* shouldn't happen */
> -                       kunmap(vmx->nested.pi_desc_page);
> -                       kvm_release_page_dirty(vmx->nested.pi_desc_page);
> -                       vmx->nested.pi_desc_page = NULL;
> -                       vmx->nested.pi_desc = NULL;
> -                       vmcs_write64(POSTED_INTR_DESC_ADDR, -1ull);
> +               map = &vmx->nested.pi_desc_map;
> +
> +               if (!kvm_vcpu_map(vcpu, gpa_to_gfn(vmcs12->posted_intr_desc_addr), map)) {
> +                       vmx->nested.pi_desc =
> +                               (struct pi_desc *)(((void *)map->hva) +
> +                               offset_in_page(vmcs12->posted_intr_desc_addr));
> +                       vmcs_write64(POSTED_INTR_DESC_ADDR,
> +                                    pfn_to_hpa(map->pfn) + offset_in_page(vmcs12->posted_intr_desc_addr));
>                 }

Previously, if there was no backing page for the
vmcs12->posted_intr_desc_addr, we wrote an illegal value (-1ull) into
the vmcs02 POSTED_INTR_DESC_ADDR field to force VM-entry failure. Now,
AFAICT, we leave that field unmodified. For a newly constructed
vmcs02, doesn't that mean we're going to treat physical address 0 as
the address of the vmcs02 posted interrupt descriptor?

> -               page = kvm_vcpu_gpa_to_page(vcpu, vmcs12->posted_intr_desc_addr);
> -               if (is_error_page(page))
> -                       return;
> -               vmx->nested.pi_desc_page = page;
> -               vmx->nested.pi_desc = kmap(vmx->nested.pi_desc_page);
> -               vmx->nested.pi_desc =
> -                       (struct pi_desc *)((void *)vmx->nested.pi_desc +
> -                       (unsigned long)(vmcs12->posted_intr_desc_addr &
> -                       (PAGE_SIZE - 1)));
> -               vmcs_write64(POSTED_INTR_DESC_ADDR,
> -                       page_to_phys(vmx->nested.pi_desc_page) +
> -                       (unsigned long)(vmcs12->posted_intr_desc_addr &
> -                       (PAGE_SIZE - 1)));
>         }
>         if (nested_vmx_prepare_msr_bitmap(vcpu, vmcs12))
>                 vmcs_set_bits(CPU_BASED_VM_EXEC_CONTROL,
> @@ -3911,12 +3896,8 @@ void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
>                 vmx->nested.apic_access_page = NULL;
>         }
>         kvm_vcpu_unmap(vcpu, &vmx->nested.virtual_apic_map, true);
> -       if (vmx->nested.pi_desc_page) {
> -               kunmap(vmx->nested.pi_desc_page);
> -               kvm_release_page_dirty(vmx->nested.pi_desc_page);
> -               vmx->nested.pi_desc_page = NULL;
> -               vmx->nested.pi_desc = NULL;
> -       }
> +       kvm_vcpu_unmap(vcpu, &vmx->nested.pi_desc_map, true);
> +       vmx->nested.pi_desc = NULL;
>
>         /*
>          * We are now running in L2, mmu_notifier will force to reload the
> diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
> index f618f52..bd04725 100644
> --- a/arch/x86/kvm/vmx/vmx.h
> +++ b/arch/x86/kvm/vmx/vmx.h
> @@ -143,7 +143,7 @@ struct nested_vmx {
>          */
>         struct page *apic_access_page;
>         struct kvm_host_map virtual_apic_map;
> -       struct page *pi_desc_page;
> +       struct kvm_host_map pi_desc_map;
>
>         struct kvm_host_map msr_bitmap_map;
>
> --
> 2.7.4
>

Re: [PATCH v6 08/14] KVM/nVMX: Use kvm_vcpu_map when mapping the posted interrupt descriptor table

[Sean Christopherson]

On Thu, May 06, 2021, Jim Mattson wrote:
> On Thu, Jan 31, 2019 at 12:28 PM KarimAllah Ahmed <karahmed@amazon.de> wrote:
> >
> > Use kvm_vcpu_map when mapping the posted interrupt descriptor table since
> > using kvm_vcpu_gpa_to_page() and kmap() will only work for guest memory
> > that has a "struct page".
> >
> > One additional semantic change is that the virtual host mapping lifecycle
> > has changed a bit. It now has the same lifetime of the pinning of the
> > interrupt descriptor table page on the host side.
> >
> > Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
> > Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> > ---
> > v4 -> v5:
> > - unmap with dirty flag
> >
> > v1 -> v2:
> > - Do not change the lifecycle of the mapping (pbonzini)
> > ---
> >  arch/x86/kvm/vmx/nested.c | 43 ++++++++++++-------------------------------
> >  arch/x86/kvm/vmx/vmx.h    |  2 +-
> >  2 files changed, 13 insertions(+), 32 deletions(-)
> >
> > diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> > index 31b352c..53b1063 100644
> > --- a/arch/x86/kvm/vmx/nested.c
> > +++ b/arch/x86/kvm/vmx/nested.c
> > @@ -230,12 +230,8 @@ static void free_nested(struct kvm_vcpu *vcpu)
> >                 vmx->nested.apic_access_page = NULL;
> >         }
> >         kvm_vcpu_unmap(vcpu, &vmx->nested.virtual_apic_map, true);
> > -       if (vmx->nested.pi_desc_page) {
> > -               kunmap(vmx->nested.pi_desc_page);
> > -               kvm_release_page_dirty(vmx->nested.pi_desc_page);
> > -               vmx->nested.pi_desc_page = NULL;
> > -               vmx->nested.pi_desc = NULL;
> > -       }
> > +       kvm_vcpu_unmap(vcpu, &vmx->nested.pi_desc_map, true);
> > +       vmx->nested.pi_desc = NULL;
> >
> >         kvm_mmu_free_roots(vcpu, &vcpu->arch.guest_mmu, KVM_MMU_ROOTS_ALL);
> >
> > @@ -2868,26 +2864,15 @@ static void nested_get_vmcs12_pages(struct kvm_vcpu *vcpu)
> >         }
> >
> >         if (nested_cpu_has_posted_intr(vmcs12)) {
> > -               if (vmx->nested.pi_desc_page) { /* shouldn't happen */
> > -                       kunmap(vmx->nested.pi_desc_page);
> > -                       kvm_release_page_dirty(vmx->nested.pi_desc_page);
> > -                       vmx->nested.pi_desc_page = NULL;
> > -                       vmx->nested.pi_desc = NULL;
> > -                       vmcs_write64(POSTED_INTR_DESC_ADDR, -1ull);
> > +               map = &vmx->nested.pi_desc_map;
> > +
> > +               if (!kvm_vcpu_map(vcpu, gpa_to_gfn(vmcs12->posted_intr_desc_addr), map)) {
> > +                       vmx->nested.pi_desc =
> > +                               (struct pi_desc *)(((void *)map->hva) +
> > +                               offset_in_page(vmcs12->posted_intr_desc_addr));
> > +                       vmcs_write64(POSTED_INTR_DESC_ADDR,
> > +                                    pfn_to_hpa(map->pfn) + offset_in_page(vmcs12->posted_intr_desc_addr));
> >                 }
> 
> Previously, if there was no backing page for the
> vmcs12->posted_intr_desc_addr, we wrote an illegal value (-1ull) into
> the vmcs02 POSTED_INTR_DESC_ADDR field to force VM-entry failure.

The "vmcs_write64(POSTED_INTR_DESC_ADDR, -1ull)" above is for the "impossible"
case where the PI descriptor was already mapped.  The error handling for failure
to map is below.  The (forced) VM-Exit unmap paths don't stuff vmcs02 either.
In other words, I think the bug was pre-existing.

> Now, AFAICT, we leave that field unmodified. For a newly constructed vmcs02,
> doesn't that mean we're going to treat physical address 0 as the address of
> the vmcs02 posted interrupt descriptor?

PA=0 is the happy path.  Thanks to L1TF, that memory is always unused.  If
mapping for a previous VM-Enter succeeded, vmcs02.POSTED_INTR_DESC_ADDR will
hold whatever PA was used for the last VM-Enter.
 
> > -               page = kvm_vcpu_gpa_to_page(vcpu, vmcs12->posted_intr_desc_addr);
> > -               if (is_error_page(page))
> > -                       return;

Error path for failure to map.

> > -               vmx->nested.pi_desc_page = page;
> > -               vmx->nested.pi_desc = kmap(vmx->nested.pi_desc_page);
> > -               vmx->nested.pi_desc =
> > -                       (struct pi_desc *)((void *)vmx->nested.pi_desc +
> > -                       (unsigned long)(vmcs12->posted_intr_desc_addr &
> > -                       (PAGE_SIZE - 1)));
> > -               vmcs_write64(POSTED_INTR_DESC_ADDR,
> > -                       page_to_phys(vmx->nested.pi_desc_page) +
> > -                       (unsigned long)(vmcs12->posted_intr_desc_addr &
> > -                       (PAGE_SIZE - 1)));
> >         }
> >         if (nested_vmx_prepare_msr_bitmap(vcpu, vmcs12))
> >                 vmcs_set_bits(CPU_BASED_VM_EXEC_CONTROL,
> > @@ -3911,12 +3896,8 @@ void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
> >                 vmx->nested.apic_access_page = NULL;
> >         }
> >         kvm_vcpu_unmap(vcpu, &vmx->nested.virtual_apic_map, true);
> > -       if (vmx->nested.pi_desc_page) {
> > -               kunmap(vmx->nested.pi_desc_page);
> > -               kvm_release_page_dirty(vmx->nested.pi_desc_page);
> > -               vmx->nested.pi_desc_page = NULL;
> > -               vmx->nested.pi_desc = NULL;
> > -       }
> > +       kvm_vcpu_unmap(vcpu, &vmx->nested.pi_desc_map, true);
> > +       vmx->nested.pi_desc = NULL;
> >
> >         /*
> >          * We are now running in L2, mmu_notifier will force to reload the
> > diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
> > index f618f52..bd04725 100644
> > --- a/arch/x86/kvm/vmx/vmx.h
> > +++ b/arch/x86/kvm/vmx/vmx.h
> > @@ -143,7 +143,7 @@ struct nested_vmx {
> >          */
> >         struct page *apic_access_page;
> >         struct kvm_host_map virtual_apic_map;
> > -       struct page *pi_desc_page;
> > +       struct kvm_host_map pi_desc_map;
> >
> >         struct kvm_host_map msr_bitmap_map;
> >
> > --
> > 2.7.4
> >