[Patch v4 00/13] Add PCI pass-thru support to Hyper-V Confidential VMs

[Patch v4 00/13] Add PCI pass-thru support to Hyper-V Confidential VMs

[Michael Kelley]

This patch series adds support for PCI pass-thru devices to Hyper-V
Confidential VMs (also called "Isolation VMs"). But in preparation, it
first changes how private (encrypted) vs. shared (decrypted) memory is
handled in Hyper-V SEV-SNP guest VMs. The new approach builds on the
confidential computing (coco) mechanisms introduced in the 5.19 kernel
for TDX support and significantly reduces the amount of Hyper-V specific
code. Furthermore, with this new approach a proposed RFC patch set for
generic DMA layer functionality[1] is no longer necessary.

Background
==========
Hyper-V guests on AMD SEV-SNP hardware have the option of using the
"virtual Top Of Memory" (vTOM) feature specified by the SEV-SNP
architecture. With vTOM, shared vs. private memory accesses are
controlled by splitting the guest physical address space into two
halves.  vTOM is the dividing line where the uppermost bit of the
physical address space is set; e.g., with 47 bits of guest physical
address space, vTOM is 0x400000000000 (bit 46 is set).  Guest physical
memory is accessible at two parallel physical addresses -- one below
vTOM and one above vTOM.  Accesses below vTOM are private (encrypted)
while accesses above vTOM are shared (decrypted). In this sense, vTOM
is like the GPA.SHARED bit in Intel TDX.

In Hyper-V's use of vTOM, the normal guest OS runs at VMPL2, while
a Hyper-V provided "paravisor" runs at VMPL0 in the guest VM. (VMPL is
Virtual Machine Privilege Level. See AMD's SEV-SNP spec for more
details.) The paravisor provides emulation for various system devices
like the IO-APIC as part of the guest VM.  Accesses to such devices
made by the normal guest OS trap to the paravisor and are emulated in
the guest VM context instead of in the Hyper-V host. This emulation is
invisible to the normal guest OS, but with the quirk that memory mapped
I/O accesses to these devices must be treated as private, not shared as
would be the case for other device accesses.

Support for Hyper-V guests using vTOM was added to the Linux kernel
in two patch sets[2][3]. This support treats the vTOM bit as part of
the physical address.  For accessing shared (decrypted) memory, the core
approach is to create a second kernel virtual mapping that maps to
parallel physical addresses above vTOM, while leaving the original
mapping unchanged.  Most of the code for creating that second virtual
mapping is confined to Hyper-V specific areas, but there are are also
changes to generic swiotlb code.

Changes in this patch set
=========================
In preparation for supporting PCI pass-thru devices, this patch set
changes the core approach for handling vTOM. In the new approach,
the vTOM bit is treated as a protection flag, and not as part of
the physical address. This new approach is like the approach for
the GPA.SHARED bit in Intel TDX.  Furthermore, there's no need to
create a second kernel virtual mapping.  When memory is changed
between private and shared using set_memory_decrypted() and
set_memory_encrypted(), the PTEs for the existing kernel mapping
are changed to add or remove the vTOM bit just as with TDX. The
hypercalls to change the memory status on the host side are made
using the existing callback mechanism. Everything just works, with
a minor tweak to map the IO-APIC to use private accesses as mentioned
above.

With the new handling of vTOM in place, existing Hyper-V code that
creates the second kernel virtual mapping still works, but it is now
redundant as the original kernel virtual mapping (as updated) maps
to the same physical address. To simplify things going forward, this
patch set removes the code that creates the second kernel virtual
mapping. And since a second kernel virtual mapping is no longer
needed, changes to the DMA layer proposed as an RFC[1] are no
longer needed.

Finally, to support PCI pass-thru in a Confidential VM, Hyper-V
requires that all accesses to PCI config space be emulated using
a hypercall.  This patch set adds functions to invoke those
hypercalls and uses them in the config space access functions
in the Hyper-V PCI driver. Lastly, the Hyper-V PCI driver is
marked as allowed to be used in a Confidential VM.  The Hyper-V
PCI driver has been hardened against a malicious Hyper-V in a
previous patch set.[4]

Patch Organization
==================
Patches 1 thru 5 are prepatory patches that account for
slightly different assumptions when running in a Hyper-V VM
with vTOM, fix some minor bugs, and make temporary tweaks
to avoid needing a single large patch to make the transition
from the old approach to the new approach.

Patch 6 enables the new approach to handling vTOM for Hyper-V
guest VMs. This is the core patch after which the new approach
is in effect.

Patches 7 thru 10 remove existing code for creating the second
kernel virtual mapping that is no longer necessary with the
new approach.

Patch 11 updates existing code so that it no longer assumes that
the vTOM bit is part of the physical address.

Patches 12 and 13 add new hypercalls for accessing MMIO space
and use those hypercalls for PCI config space. They also enable
the Hyper-V vPCI driver to be used in a Confidential VM.

[1] https://lore.kernel.org/lkml/20220706195027.76026-1-parri.andrea@gmail.com/
[2] https://lore.kernel.org/all/20211025122116.264793-1-ltykernel@gmail.com/
[3] https://lore.kernel.org/all/20211213071407.314309-1-ltykernel@gmail.com/
[4] https://lore.kernel.org/all/20220511223207.3386-1-parri.andrea@gmail.com/

---

Changes in v4:
* Remove previous Patch 1 from this series and submit separately
  [Dave Hansen & Boris Petkov]

* Patch 1: Change the name of the new CC_ATTR that controls
  whether the IO-APIC is mapped decrypted [Boris Petkov]

* Patch 4: Use sme_me_mask directly instead of calling the
  getter function. Add Fixes: tag. [Tom Lendacky]

* Patch 6: Remove CC_VENDOR_HYPERV and merge associated
  vTOM functionality under CC_VENDOR_AMD. [Boris Petkov]

* Patch 8: Use bitwise OR to pick up the vTOM bit in
  shared_gpa_boundary rather than adding it

Changes in v3:
* Patch 1: Tweak the code fix to cleanly separate the page
  alignment and physical address masking [Dave Hansen]

* Patch 2: Change the name of the new CC_ATTR that controls
  whether the IO-APIC is mapped decrypted [Dave Hansen]

* Patch 5 (now patch 7): Add CC_ATTR_MEM_ENCRYPT to what
  Hyper-V vTOM reports as 'true'. With the addition, Patches
  5 and 6 are new to accomodate working correctly with Hyper-V
  VMs using vTOM. [Tom Lendacky]

Changes in v2:
* Patch 11: Include more detail in the error message if an MMIO
  hypercall fails. [Bjorn Helgaas]

* Patch 12: Restore removed memory barriers. It seems like these
  barriers should not be needed because of the spin_unlock() calls,
  but commit bdd74440d9e8 indicates that they are. This patch series
  will leave the barriers unchanged; whether they are really needed
  can be sorted out separately. [Boqun Feng]

Michael Kelley (13):
  x86/ioapic: Gate decrypted mapping on cc_platform_has() attribute
  x86/hyperv: Reorder code in prep for subsequent patch
  Drivers: hv: Explicitly request decrypted in vmap_pfn() calls
  x86/mm: Handle decryption/re-encryption of bss_decrypted consistently
  init: Call mem_encrypt_init() after Hyper-V hypercall init is done
  x86/hyperv: Change vTOM handling to use standard coco mechanisms
  swiotlb: Remove bounce buffer remapping for Hyper-V
  Drivers: hv: vmbus: Remove second mapping of VMBus monitor pages
  Drivers: hv: vmbus: Remove second way of mapping ring buffers
  hv_netvsc: Remove second mapping of send and recv buffers
  Drivers: hv: Don't remap addresses that are above shared_gpa_boundary
  PCI: hv: Add hypercalls to read/write MMIO space
  PCI: hv: Enable PCI pass-thru devices in Confidential VMs

 arch/x86/coco/core.c                |  37 ++++--
 arch/x86/hyperv/hv_init.c           |  18 +--
 arch/x86/hyperv/ivm.c               | 128 ++++++++++----------
 arch/x86/include/asm/coco.h         |   1 -
 arch/x86/include/asm/hyperv-tlfs.h  |   3 +
 arch/x86/include/asm/mshyperv.h     |   8 +-
 arch/x86/include/asm/msr-index.h    |   1 +
 arch/x86/kernel/apic/io_apic.c      |   3 +-
 arch/x86/kernel/cpu/mshyperv.c      |  22 ++--
 arch/x86/mm/mem_encrypt_amd.c       |  10 +-
 arch/x86/mm/pat/set_memory.c        |   3 -
 drivers/hv/Kconfig                  |   1 -
 drivers/hv/channel_mgmt.c           |   2 +-
 drivers/hv/connection.c             | 113 +++++-------------
 drivers/hv/hv.c                     |  23 ++--
 drivers/hv/hv_common.c              |  11 --
 drivers/hv/hyperv_vmbus.h           |   2 -
 drivers/hv/ring_buffer.c            |  62 ++++------
 drivers/net/hyperv/hyperv_net.h     |   2 -
 drivers/net/hyperv/netvsc.c         |  48 +-------
 drivers/pci/controller/pci-hyperv.c | 232 ++++++++++++++++++++++++++----------
 include/asm-generic/hyperv-tlfs.h   |  22 ++++
 include/asm-generic/mshyperv.h      |   2 -
 include/linux/cc_platform.h         |  12 ++
 include/linux/swiotlb.h             |   2 -
 init/main.c                         |  19 +--
 kernel/dma/swiotlb.c                |  45 +------
 27 files changed, 398 insertions(+), 434 deletions(-)

-- 
1.8.3.1

[Patch v4 01/13] x86/ioapic: Gate decrypted mapping on cc_platform_has() attribute

[Michael Kelley]

Current code always maps the IO-APIC as shared (decrypted) in a
confidential VM. But Hyper-V guest VMs on AMD SEV-SNP with vTOM
enabled use a paravisor running in VMPL0 to emulate the IO-APIC.
In such a case, the IO-APIC must be accessed as private (encrypted).

Fix this by gating the IO-APIC decrypted mapping on a new
cc_platform_has() attribute that a subsequent patch in the series
will set only for guests using vTOM.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Wei Liu <wei.liu@kernel.org>
---
 arch/x86/kernel/apic/io_apic.c |  3 ++-
 include/linux/cc_platform.h    | 12 ++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index a868b76..2b70e2e 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2686,7 +2686,8 @@ static void io_apic_set_fixmap(enum fixed_addresses idx, phys_addr_t phys)
 	 * Ensure fixmaps for IOAPIC MMIO respect memory encryption pgprot
 	 * bits, just like normal ioremap():
 	 */
-	flags = pgprot_decrypted(flags);
+	if (!cc_platform_has(CC_ATTR_ACCESS_IOAPIC_ENCRYPTED))
+		flags = pgprot_decrypted(flags);
 
 	__set_fixmap(idx, phys, flags);
 }
diff --git a/include/linux/cc_platform.h b/include/linux/cc_platform.h
index cb0d6cd..7b63a7d 100644
--- a/include/linux/cc_platform.h
+++ b/include/linux/cc_platform.h
@@ -90,6 +90,18 @@ enum cc_attr {
 	 * Examples include TDX Guest.
 	 */
 	CC_ATTR_HOTPLUG_DISABLED,
+
+	/**
+	 * @CC_ATTR_ACCESS_IOAPIC_ENCRYPTED: Guest VM IO-APIC is encrypted
+	 *
+	 * The platform/OS is running as a guest/virtual machine with
+	 * an IO-APIC that is emulated by a paravisor running in the
+	 * guest VM context. As such, the IO-APIC is accessed in the
+	 * encrypted portion of the guest physical address space.
+	 *
+	 * Examples include Hyper-V SEV-SNP guests using vTOM.
+	 */
+	CC_ATTR_ACCESS_IOAPIC_ENCRYPTED,
 };
 
 #ifdef CONFIG_ARCH_HAS_CC_PLATFORM
-- 
1.8.3.1

[Patch v4 02/13] x86/hyperv: Reorder code in prep for subsequent patch

[Michael Kelley]

Reorder some code as preparation for a subsequent patch.  No
functional change.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
---
 arch/x86/hyperv/ivm.c | 68 +++++++++++++++++++++++++--------------------------
 1 file changed, 34 insertions(+), 34 deletions(-)

diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index 1dbcbd9..f33c67e 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -235,40 +235,6 @@ void hv_ghcb_msr_read(u64 msr, u64 *value)
 EXPORT_SYMBOL_GPL(hv_ghcb_msr_read);
 #endif
 
-enum hv_isolation_type hv_get_isolation_type(void)
-{
-	if (!(ms_hyperv.priv_high & HV_ISOLATION))
-		return HV_ISOLATION_TYPE_NONE;
-	return FIELD_GET(HV_ISOLATION_TYPE, ms_hyperv.isolation_config_b);
-}
-EXPORT_SYMBOL_GPL(hv_get_isolation_type);
-
-/*
- * hv_is_isolation_supported - Check system runs in the Hyper-V
- * isolation VM.
- */
-bool hv_is_isolation_supported(void)
-{
-	if (!cpu_feature_enabled(X86_FEATURE_HYPERVISOR))
-		return false;
-
-	if (!hypervisor_is_type(X86_HYPER_MS_HYPERV))
-		return false;
-
-	return hv_get_isolation_type() != HV_ISOLATION_TYPE_NONE;
-}
-
-DEFINE_STATIC_KEY_FALSE(isolation_type_snp);
-
-/*
- * hv_isolation_type_snp - Check system runs in the AMD SEV-SNP based
- * isolation VM.
- */
-bool hv_isolation_type_snp(void)
-{
-	return static_branch_unlikely(&isolation_type_snp);
-}
-
 /*
  * hv_mark_gpa_visibility - Set pages visible to host via hvcall.
  *
@@ -387,3 +353,37 @@ void hv_unmap_memory(void *addr)
 {
 	vunmap(addr);
 }
+
+enum hv_isolation_type hv_get_isolation_type(void)
+{
+	if (!(ms_hyperv.priv_high & HV_ISOLATION))
+		return HV_ISOLATION_TYPE_NONE;
+	return FIELD_GET(HV_ISOLATION_TYPE, ms_hyperv.isolation_config_b);
+}
+EXPORT_SYMBOL_GPL(hv_get_isolation_type);
+
+/*
+ * hv_is_isolation_supported - Check system runs in the Hyper-V
+ * isolation VM.
+ */
+bool hv_is_isolation_supported(void)
+{
+	if (!cpu_feature_enabled(X86_FEATURE_HYPERVISOR))
+		return false;
+
+	if (!hypervisor_is_type(X86_HYPER_MS_HYPERV))
+		return false;
+
+	return hv_get_isolation_type() != HV_ISOLATION_TYPE_NONE;
+}
+
+DEFINE_STATIC_KEY_FALSE(isolation_type_snp);
+
+/*
+ * hv_isolation_type_snp - Check system runs in the AMD SEV-SNP based
+ * isolation VM.
+ */
+bool hv_isolation_type_snp(void)
+{
+	return static_branch_unlikely(&isolation_type_snp);
+}
-- 
1.8.3.1

[Patch v4 03/13] Drivers: hv: Explicitly request decrypted in vmap_pfn() calls

[Michael Kelley]

In preparation for a subsequent patch, update vmap_pfn() calls to
explicitly request that the mapping be for decrypted access to
the memory.  There's no change in functionality since the PFNs
passed to vmap_pfn() are above the shared_gpa_boundary, implicitly
producing a decrypted mapping. But explicitly requesting decrypted
allows the code to work before and after a subsequent patch
that will cause vmap_pfn() to mask the PFNs to being below the
shared_gpa_boundary. While another subsesquent patch removes the
vmap_pfn() calls entirely, this temporary tweak avoids the need
for a large patch that makes all the changes at once.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
---
 arch/x86/hyperv/ivm.c    | 2 +-
 drivers/hv/ring_buffer.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index f33c67e..e8be4c2 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -343,7 +343,7 @@ void *hv_map_memory(void *addr, unsigned long size)
 		pfns[i] = vmalloc_to_pfn(addr + i * PAGE_SIZE) +
 			(ms_hyperv.shared_gpa_boundary >> PAGE_SHIFT);
 
-	vaddr = vmap_pfn(pfns, size / PAGE_SIZE, PAGE_KERNEL_IO);
+	vaddr = vmap_pfn(pfns, size / PAGE_SIZE, pgprot_decrypted(PAGE_KERNEL_NOENC));
 	kfree(pfns);
 
 	return vaddr;
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index c6692fd..57667b29 100644
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -211,7 +211,7 @@ int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
 
 		ring_info->ring_buffer = (struct hv_ring_buffer *)
 			vmap_pfn(pfns_wraparound, page_cnt * 2 - 1,
-				 PAGE_KERNEL);
+				 pgprot_decrypted(PAGE_KERNEL_NOENC));
 		kfree(pfns_wraparound);
 
 		if (!ring_info->ring_buffer)
-- 
1.8.3.1

[Patch v4 04/13] x86/mm: Handle decryption/re-encryption of bss_decrypted consistently

[Michael Kelley]

Current code in sme_postprocess_startup() decrypts the bss_decrypted
section when sme_me_mask is non-zero.  But code in
mem_encrypt_free_decrypted_mem() re-encrypts the unused portion based
on CC_ATTR_MEM_ENCRYPT.  In a Hyper-V guest VM using vTOM, these
conditions are not equivalent as sme_me_mask is always zero when
using vTOM.  Consequently, mem_encrypt_free_decrypted_mem() attempts
to re-encrypt memory that was never decrypted.

Fix this in mem_encrypt_free_decrypted_mem() by conditioning the
re-encryption on the same test for non-zero sme_me_mask.  Hyper-V
guests using vTOM don't need the bss_decrypted section to be
decrypted, so skipping the decryption/re-encryption doesn't cause
a problem.

Fixes: e9d1d2bb75b2 ("treewide: Replace the use of mem_encrypt_active() with cc_platform_has()")
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 arch/x86/mm/mem_encrypt_amd.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/x86/mm/mem_encrypt_amd.c b/arch/x86/mm/mem_encrypt_amd.c
index 9c4d8db..e0b51c0 100644
--- a/arch/x86/mm/mem_encrypt_amd.c
+++ b/arch/x86/mm/mem_encrypt_amd.c
@@ -513,10 +513,14 @@ void __init mem_encrypt_free_decrypted_mem(void)
 	npages = (vaddr_end - vaddr) >> PAGE_SHIFT;
 
 	/*
-	 * The unused memory range was mapped decrypted, change the encryption
-	 * attribute from decrypted to encrypted before freeing it.
+	 * If the unused memory range was mapped decrypted, change the encryption
+	 * attribute from decrypted to encrypted before freeing it. Base the
+	 * re-encryption on the same condition used for the decryption in
+	 * sme_postprocess_startup(). Higher level abstractions, such as
+	 * CC_ATTR_MEM_ENCRYPT, aren't necessarily equivalent in a Hyper-V VM
+	 * using vTOM, where sme_me_mask is always zero.
 	 */
-	if (cc_platform_has(CC_ATTR_MEM_ENCRYPT)) {
+	if (sme_me_mask) {
 		r = set_memory_encrypted(vaddr, npages);
 		if (r) {
 			pr_warn("failed to free unused decrypted pages\n");
-- 
1.8.3.1

[Patch v4 05/13] init: Call mem_encrypt_init() after Hyper-V hypercall init is done

[Michael Kelley]

Full Hyper-V initialization, including support for hypercalls, is done
as an apic_post_init callback via late_time_init().  mem_encrypt_init()
needs to make hypercalls when it marks swiotlb memory as decrypted.
But mem_encrypt_init() is currently called a few lines before
late_time_init(), so the hypercalls don't work.

Fix this by moving mem_encrypt_init() after late_time_init() and
related clock initializations. The intervening initializations don't
do any I/O that requires the swiotlb, so moving mem_encrypt_init()
slightly later has no impact.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 init/main.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/init/main.c b/init/main.c
index e1c3911..5a7c466 100644
--- a/init/main.c
+++ b/init/main.c
@@ -1088,14 +1088,6 @@ asmlinkage __visible void __init __no_sanitize_address start_kernel(void)
 	 */
 	locking_selftest();
 
-	/*
-	 * This needs to be called before any devices perform DMA
-	 * operations that might use the SWIOTLB bounce buffers. It will
-	 * mark the bounce buffers as decrypted so that their usage will
-	 * not cause "plain-text" data to be decrypted when accessed.
-	 */
-	mem_encrypt_init();
-
 #ifdef CONFIG_BLK_DEV_INITRD
 	if (initrd_start && !initrd_below_start_ok &&
 	    page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
@@ -1112,6 +1104,17 @@ asmlinkage __visible void __init __no_sanitize_address start_kernel(void)
 		late_time_init();
 	sched_clock_init();
 	calibrate_delay();
+
+	/*
+	 * This needs to be called before any devices perform DMA
+	 * operations that might use the SWIOTLB bounce buffers. It will
+	 * mark the bounce buffers as decrypted so that their usage will
+	 * not cause "plain-text" data to be decrypted when accessed. It
+	 * must be called after late_time_init() so that Hyper-V x86/x64
+	 * hypercalls work when the SWIOTLB bounce buffers are decrypted.
+	 */
+	mem_encrypt_init();
+
 	pid_idr_init();
 	anon_vma_init();
 #ifdef CONFIG_X86
-- 
1.8.3.1

[Patch v4 06/13] x86/hyperv: Change vTOM handling to use standard coco mechanisms

[Michael Kelley]

Hyper-V guests on AMD SEV-SNP hardware have the option of using the
"virtual Top Of Memory" (vTOM) feature specified by the SEV-SNP
architecture. With vTOM, shared vs. private memory accesses are
controlled by splitting the guest physical address space into two
halves.  vTOM is the dividing line where the uppermost bit of the
physical address space is set; e.g., with 47 bits of guest physical
address space, vTOM is 0x400000000000 (bit 46 is set).  Guest physical
memory is accessible at two parallel physical addresses -- one below
vTOM and one above vTOM.  Accesses below vTOM are private (encrypted)
while accesses above vTOM are shared (decrypted). In this sense, vTOM
is like the GPA.SHARED bit in Intel TDX.

Support for Hyper-V guests using vTOM was added to the Linux kernel in
two patch sets[1][2]. This support treats the vTOM bit as part of
the physical address. For accessing shared (decrypted) memory, these
patch sets create a second kernel virtual mapping that maps to physical
addresses above vTOM.

A better approach is to treat the vTOM bit as a protection flag, not
as part of the physical address. This new approach is like the approach
for the GPA.SHARED bit in Intel TDX. Rather than creating a second kernel
virtual mapping, the existing mapping is updated using recently added
coco mechanisms.  When memory is changed between private and shared using
set_memory_decrypted() and set_memory_encrypted(), the PTEs for the
existing kernel mapping are changed to add or remove the vTOM bit
in the guest physical address, just as with TDX. The hypercalls to
change the memory status on the host side are made using the existing
callback mechanism. Everything just works, with a minor tweak to map
the IO-APIC to use private accesses.

To accomplish the switch in approach, the following must be done in
this single patch:

* Update Hyper-V initialization to set the cc_mask based on vTOM
  and do other coco initialization.

* Update physical_mask so the vTOM bit is no longer treated as part
  of the physical address

* Remove CC_VENDOR_HYPERV and merge the associated vTOM functionality
  under CC_VENDOR_AMD. Update cc_mkenc() and cc_mkdec() to set/clear
  the vTOM bit as a protection flag.

* Code already exists to make hypercalls to inform Hyper-V about pages
  changing between shared and private.  Update this code to run as a
  callback from __set_memory_enc_pgtable().

* Remove the Hyper-V special case from __set_memory_enc_dec()

* Remove the Hyper-V specific call to swiotlb_update_mem_attributes()
  since mem_encrypt_init() will now do it.

[1] https://lore.kernel.org/all/20211025122116.264793-1-ltykernel@gmail.com/
[2] https://lore.kernel.org/all/20211213071407.314309-1-ltykernel@gmail.com/

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
---
 arch/x86/coco/core.c             | 37 ++++++++++++++++++++--------
 arch/x86/hyperv/hv_init.c        | 11 ---------
 arch/x86/hyperv/ivm.c            | 52 +++++++++++++++++++++++++++++++---------
 arch/x86/include/asm/coco.h      |  1 -
 arch/x86/include/asm/mshyperv.h  |  8 ++-----
 arch/x86/include/asm/msr-index.h |  1 +
 arch/x86/kernel/cpu/mshyperv.c   | 15 ++++++------
 arch/x86/mm/pat/set_memory.c     |  3 ---
 8 files changed, 78 insertions(+), 50 deletions(-)

diff --git a/arch/x86/coco/core.c b/arch/x86/coco/core.c
index 49b44f8..c361c52 100644
--- a/arch/x86/coco/core.c
+++ b/arch/x86/coco/core.c
@@ -44,6 +44,24 @@ static bool intel_cc_platform_has(enum cc_attr attr)
 static bool amd_cc_platform_has(enum cc_attr attr)
 {
 #ifdef CONFIG_AMD_MEM_ENCRYPT
+
+	/*
+	 * Handle the SEV-SNP vTOM case where sme_me_mask must be zero,
+	 * and the other levels of SME/SEV functionality, including C-bit
+	 * based SEV-SNP, must not be enabled.
+	 */
+	if (sev_status & MSR_AMD64_SNP_VTOM_ENABLED) {
+		switch (attr) {
+		case CC_ATTR_GUEST_MEM_ENCRYPT:
+		case CC_ATTR_MEM_ENCRYPT:
+		case CC_ATTR_ACCESS_IOAPIC_ENCRYPTED:
+			return true;
+		default:
+			return false;
+		}
+	}
+
+	/* Handle the C-bit case */
 	switch (attr) {
 	case CC_ATTR_MEM_ENCRYPT:
 		return sme_me_mask;
@@ -76,11 +94,6 @@ static bool amd_cc_platform_has(enum cc_attr attr)
 #endif
 }
 
-static bool hyperv_cc_platform_has(enum cc_attr attr)
-{
-	return attr == CC_ATTR_GUEST_MEM_ENCRYPT;
-}
-
 bool cc_platform_has(enum cc_attr attr)
 {
 	switch (vendor) {
@@ -88,8 +101,6 @@ bool cc_platform_has(enum cc_attr attr)
 		return amd_cc_platform_has(attr);
 	case CC_VENDOR_INTEL:
 		return intel_cc_platform_has(attr);
-	case CC_VENDOR_HYPERV:
-		return hyperv_cc_platform_has(attr);
 	default:
 		return false;
 	}
@@ -103,11 +114,14 @@ u64 cc_mkenc(u64 val)
 	 * encryption status of the page.
 	 *
 	 * - for AMD, bit *set* means the page is encrypted
-	 * - for Intel *clear* means encrypted.
+	 * - for AMD with vTOM and for Intel, *clear* means encrypted
 	 */
 	switch (vendor) {
 	case CC_VENDOR_AMD:
-		return val | cc_mask;
+		if (sev_status & MSR_AMD64_SNP_VTOM_ENABLED)
+			return val & ~cc_mask;
+		else
+			return val | cc_mask;
 	case CC_VENDOR_INTEL:
 		return val & ~cc_mask;
 	default:
@@ -120,7 +134,10 @@ u64 cc_mkdec(u64 val)
 	/* See comment in cc_mkenc() */
 	switch (vendor) {
 	case CC_VENDOR_AMD:
-		return val & ~cc_mask;
+		if (sev_status & MSR_AMD64_SNP_VTOM_ENABLED)
+			return val | cc_mask;
+		else
+			return val & ~cc_mask;
 	case CC_VENDOR_INTEL:
 		return val | cc_mask;
 	default:
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index a823fde..6dbfb26 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -29,7 +29,6 @@
 #include <linux/syscore_ops.h>
 #include <clocksource/hyperv_timer.h>
 #include <linux/highmem.h>
-#include <linux/swiotlb.h>
 
 int hyperv_init_cpuhp;
 u64 hv_current_partition_id = ~0ull;
@@ -504,16 +503,6 @@ void __init hyperv_init(void)
 	/* Query the VMs extended capability once, so that it can be cached. */
 	hv_query_ext_cap(0);
 
-#ifdef CONFIG_SWIOTLB
-	/*
-	 * Swiotlb bounce buffer needs to be mapped in extra address
-	 * space. Map function doesn't work in the early place and so
-	 * call swiotlb_update_mem_attributes() here.
-	 */
-	if (hv_is_isolation_supported())
-		swiotlb_update_mem_attributes();
-#endif
-
 	return;
 
 clean_guest_os_id:
diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index e8be4c2..8e2717d 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -13,6 +13,8 @@
 #include <asm/svm.h>
 #include <asm/sev.h>
 #include <asm/io.h>
+#include <asm/coco.h>
+#include <asm/mem_encrypt.h>
 #include <asm/mshyperv.h>
 #include <asm/hypervisor.h>
 
@@ -233,7 +235,6 @@ void hv_ghcb_msr_read(u64 msr, u64 *value)
 	local_irq_restore(flags);
 }
 EXPORT_SYMBOL_GPL(hv_ghcb_msr_read);
-#endif
 
 /*
  * hv_mark_gpa_visibility - Set pages visible to host via hvcall.
@@ -286,27 +287,25 @@ static int hv_mark_gpa_visibility(u16 count, const u64 pfn[],
 }
 
 /*
- * hv_set_mem_host_visibility - Set specified memory visible to host.
+ * hv_vtom_set_host_visibility - Set specified memory visible to host.
  *
  * In Isolation VM, all guest memory is encrypted from host and guest
  * needs to set memory visible to host via hvcall before sharing memory
  * with host. This function works as wrap of hv_mark_gpa_visibility()
  * with memory base and size.
  */
-int hv_set_mem_host_visibility(unsigned long kbuffer, int pagecount, bool visible)
+static bool hv_vtom_set_host_visibility(unsigned long kbuffer, int pagecount, bool enc)
 {
-	enum hv_mem_host_visibility visibility = visible ?
-			VMBUS_PAGE_VISIBLE_READ_WRITE : VMBUS_PAGE_NOT_VISIBLE;
+	enum hv_mem_host_visibility visibility = enc ?
+			VMBUS_PAGE_NOT_VISIBLE : VMBUS_PAGE_VISIBLE_READ_WRITE;
 	u64 *pfn_array;
 	int ret = 0;
+	bool result = true;
 	int i, pfn;
 
-	if (!hv_is_isolation_supported() || !hv_hypercall_pg)
-		return 0;
-
 	pfn_array = kmalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);
 	if (!pfn_array)
-		return -ENOMEM;
+		return false;
 
 	for (i = 0, pfn = 0; i < pagecount; i++) {
 		pfn_array[pfn] = virt_to_hvpfn((void *)kbuffer + i * HV_HYP_PAGE_SIZE);
@@ -315,17 +314,48 @@ int hv_set_mem_host_visibility(unsigned long kbuffer, int pagecount, bool visibl
 		if (pfn == HV_MAX_MODIFY_GPA_REP_COUNT || i == pagecount - 1) {
 			ret = hv_mark_gpa_visibility(pfn, pfn_array,
 						     visibility);
-			if (ret)
+			if (ret) {
+				result = false;
 				goto err_free_pfn_array;
+			}
 			pfn = 0;
 		}
 	}
 
  err_free_pfn_array:
 	kfree(pfn_array);
-	return ret;
+	return result;
+}
+
+static bool hv_vtom_tlb_flush_required(bool private)
+{
+	return true;
 }
 
+static bool hv_vtom_cache_flush_required(void)
+{
+	return false;
+}
+
+void __init hv_vtom_init(void)
+{
+	/*
+	 * By design, a VM using vTOM doesn't see the SEV setting,
+	 * so SEV initialization is bypassed and sev_status isn't set.
+	 * Set it here to indicate a vTOM VM.
+	 */
+	sev_status = MSR_AMD64_SNP_VTOM_ENABLED;
+	cc_set_vendor(CC_VENDOR_AMD);
+	cc_set_mask(ms_hyperv.shared_gpa_boundary);
+	physical_mask &= ms_hyperv.shared_gpa_boundary - 1;
+
+	x86_platform.guest.enc_cache_flush_required = hv_vtom_cache_flush_required;
+	x86_platform.guest.enc_tlb_flush_required = hv_vtom_tlb_flush_required;
+	x86_platform.guest.enc_status_change_finish = hv_vtom_set_host_visibility;
+}
+
+#endif /* CONFIG_AMD_MEM_ENCRYPT */
+
 /*
  * hv_map_memory - map memory to extra space in the AMD SEV-SNP Isolation VM.
  */
diff --git a/arch/x86/include/asm/coco.h b/arch/x86/include/asm/coco.h
index 3d98c3a..d2c6a2e 100644
--- a/arch/x86/include/asm/coco.h
+++ b/arch/x86/include/asm/coco.h
@@ -7,7 +7,6 @@
 enum cc_vendor {
 	CC_VENDOR_NONE,
 	CC_VENDOR_AMD,
-	CC_VENDOR_HYPERV,
 	CC_VENDOR_INTEL,
 };
 
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 6d502f3..010768d 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -172,18 +172,19 @@ static inline void hv_apic_init(void) {}
 int hv_map_ioapic_interrupt(int ioapic_id, bool level, int vcpu, int vector,
 		struct hv_interrupt_entry *entry);
 int hv_unmap_ioapic_interrupt(int ioapic_id, struct hv_interrupt_entry *entry);
-int hv_set_mem_host_visibility(unsigned long addr, int numpages, bool visible);
 
 #ifdef CONFIG_AMD_MEM_ENCRYPT
 void hv_ghcb_msr_write(u64 msr, u64 value);
 void hv_ghcb_msr_read(u64 msr, u64 *value);
 bool hv_ghcb_negotiate_protocol(void);
 void hv_ghcb_terminate(unsigned int set, unsigned int reason);
+void hv_vtom_init(void);
 #else
 static inline void hv_ghcb_msr_write(u64 msr, u64 value) {}
 static inline void hv_ghcb_msr_read(u64 msr, u64 *value) {}
 static inline bool hv_ghcb_negotiate_protocol(void) { return false; }
 static inline void hv_ghcb_terminate(unsigned int set, unsigned int reason) {}
+static inline void hv_vtom_init(void) {}
 #endif
 
 extern bool hv_isolation_type_snp(void);
@@ -239,11 +240,6 @@ static inline int hyperv_flush_guest_mapping_range(u64 as,
 }
 static inline void hv_set_register(unsigned int reg, u64 value) { }
 static inline u64 hv_get_register(unsigned int reg) { return 0; }
-static inline int hv_set_mem_host_visibility(unsigned long addr, int numpages,
-					     bool visible)
-{
-	return -1;
-}
 #endif /* CONFIG_HYPERV */
 
 
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 37ff475..6a6e70e 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -565,6 +565,7 @@
 #define MSR_AMD64_SEV_ENABLED		BIT_ULL(MSR_AMD64_SEV_ENABLED_BIT)
 #define MSR_AMD64_SEV_ES_ENABLED	BIT_ULL(MSR_AMD64_SEV_ES_ENABLED_BIT)
 #define MSR_AMD64_SEV_SNP_ENABLED	BIT_ULL(MSR_AMD64_SEV_SNP_ENABLED_BIT)
+#define MSR_AMD64_SNP_VTOM_ENABLED	BIT_ULL(3)
 
 #define MSR_AMD64_VIRT_SPEC_CTRL	0xc001011f
 
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 8316139..b080795 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -33,7 +33,6 @@
 #include <asm/nmi.h>
 #include <clocksource/hyperv_timer.h>
 #include <asm/numa.h>
-#include <asm/coco.h>
 
 /* Is Linux running as the root partition? */
 bool hv_root_partition;
@@ -325,8 +324,10 @@ static void __init ms_hyperv_init_platform(void)
 	if (ms_hyperv.priv_high & HV_ISOLATION) {
 		ms_hyperv.isolation_config_a = cpuid_eax(HYPERV_CPUID_ISOLATION_CONFIG);
 		ms_hyperv.isolation_config_b = cpuid_ebx(HYPERV_CPUID_ISOLATION_CONFIG);
-		ms_hyperv.shared_gpa_boundary =
-			BIT_ULL(ms_hyperv.shared_gpa_boundary_bits);
+
+		if (ms_hyperv.shared_gpa_boundary_active)
+			ms_hyperv.shared_gpa_boundary =
+				BIT_ULL(ms_hyperv.shared_gpa_boundary_bits);
 
 		pr_info("Hyper-V: Isolation Config: Group A 0x%x, Group B 0x%x\n",
 			ms_hyperv.isolation_config_a, ms_hyperv.isolation_config_b);
@@ -337,11 +338,6 @@ static void __init ms_hyperv_init_platform(void)
 			swiotlb_unencrypted_base = ms_hyperv.shared_gpa_boundary;
 #endif
 		}
-		/* Isolation VMs are unenlightened SEV-based VMs, thus this check: */
-		if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) {
-			if (hv_get_isolation_type() != HV_ISOLATION_TYPE_NONE)
-				cc_set_vendor(CC_VENDOR_HYPERV);
-		}
 	}
 
 	if (hv_max_functions_eax >= HYPERV_CPUID_NESTED_FEATURES) {
@@ -410,6 +406,9 @@ static void __init ms_hyperv_init_platform(void)
 	i8253_clear_counter_on_shutdown = false;
 
 #if IS_ENABLED(CONFIG_HYPERV)
+	if ((hv_get_isolation_type() == HV_ISOLATION_TYPE_VBS) ||
+	    (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP))
+		hv_vtom_init();
 	/*
 	 * Setup the hook to get control post apic initialization.
 	 */
diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
index 356758b..b037954 100644
--- a/arch/x86/mm/pat/set_memory.c
+++ b/arch/x86/mm/pat/set_memory.c
@@ -2175,9 +2175,6 @@ static int __set_memory_enc_pgtable(unsigned long addr, int numpages, bool enc)
 
 static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc)
 {
-	if (hv_is_isolation_supported())
-		return hv_set_mem_host_visibility(addr, numpages, !enc);
-
 	if (cc_platform_has(CC_ATTR_MEM_ENCRYPT))
 		return __set_memory_enc_pgtable(addr, numpages, enc);
 
-- 
1.8.3.1

[Patch v4 07/13] swiotlb: Remove bounce buffer remapping for Hyper-V

[Michael Kelley]

With changes to how Hyper-V guest VMs flip memory between private
(encrypted) and shared (decrypted), creating a second kernel virtual
mapping for shared memory is no longer necessary. Everything needed
for the transition to shared is handled by set_memory_decrypted().

As such, remove swiotlb_unencrypted_base and the associated
code.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Acked-by: Christoph Hellwig <hch@lst.de>
---
 arch/x86/kernel/cpu/mshyperv.c |  7 +------
 include/linux/swiotlb.h        |  2 --
 kernel/dma/swiotlb.c           | 45 +-----------------------------------------
 3 files changed, 2 insertions(+), 52 deletions(-)

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index b080795..c87e411 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -18,7 +18,6 @@
 #include <linux/kexec.h>
 #include <linux/i8253.h>
 #include <linux/random.h>
-#include <linux/swiotlb.h>
 #include <asm/processor.h>
 #include <asm/hypervisor.h>
 #include <asm/hyperv-tlfs.h>
@@ -332,12 +331,8 @@ static void __init ms_hyperv_init_platform(void)
 		pr_info("Hyper-V: Isolation Config: Group A 0x%x, Group B 0x%x\n",
 			ms_hyperv.isolation_config_a, ms_hyperv.isolation_config_b);
 
-		if (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP) {
+		if (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP)
 			static_branch_enable(&isolation_type_snp);
-#ifdef CONFIG_SWIOTLB
-			swiotlb_unencrypted_base = ms_hyperv.shared_gpa_boundary;
-#endif
-		}
 	}
 
 	if (hv_max_functions_eax >= HYPERV_CPUID_NESTED_FEATURES) {
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index 35bc4e2..13d7075 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -185,6 +185,4 @@ static inline bool is_swiotlb_for_alloc(struct device *dev)
 }
 #endif /* CONFIG_DMA_RESTRICTED_POOL */
 
-extern phys_addr_t swiotlb_unencrypted_base;
-
 #endif /* __LINUX_SWIOTLB_H */
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index a34c38b..d3d6be0 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -73,8 +73,6 @@ struct io_tlb_slot {
 
 struct io_tlb_mem io_tlb_default_mem;
 
-phys_addr_t swiotlb_unencrypted_base;
-
 static unsigned long default_nslabs = IO_TLB_DEFAULT_SIZE >> IO_TLB_SHIFT;
 static unsigned long default_nareas;
 
@@ -210,34 +208,6 @@ static inline unsigned long nr_slots(u64 val)
 }
 
 /*
- * Remap swioltb memory in the unencrypted physical address space
- * when swiotlb_unencrypted_base is set. (e.g. for Hyper-V AMD SEV-SNP
- * Isolation VMs).
- */
-#ifdef CONFIG_HAS_IOMEM
-static void *swiotlb_mem_remap(struct io_tlb_mem *mem, unsigned long bytes)
-{
-	void *vaddr = NULL;
-
-	if (swiotlb_unencrypted_base) {
-		phys_addr_t paddr = mem->start + swiotlb_unencrypted_base;
-
-		vaddr = memremap(paddr, bytes, MEMREMAP_WB);
-		if (!vaddr)
-			pr_err("Failed to map the unencrypted memory %pa size %lx.\n",
-			       &paddr, bytes);
-	}
-
-	return vaddr;
-}
-#else
-static void *swiotlb_mem_remap(struct io_tlb_mem *mem, unsigned long bytes)
-{
-	return NULL;
-}
-#endif
-
-/*
  * Early SWIOTLB allocation may be too early to allow an architecture to
  * perform the desired operations.  This function allows the architecture to
  * call SWIOTLB when the operations are possible.  It needs to be called
@@ -246,18 +216,12 @@ static void *swiotlb_mem_remap(struct io_tlb_mem *mem, unsigned long bytes)
 void __init swiotlb_update_mem_attributes(void)
 {
 	struct io_tlb_mem *mem = &io_tlb_default_mem;
-	void *vaddr;
 	unsigned long bytes;
 
 	if (!mem->nslabs || mem->late_alloc)
 		return;
-	vaddr = phys_to_virt(mem->start);
 	bytes = PAGE_ALIGN(mem->nslabs << IO_TLB_SHIFT);
-	set_memory_decrypted((unsigned long)vaddr, bytes >> PAGE_SHIFT);
-
-	mem->vaddr = swiotlb_mem_remap(mem, bytes);
-	if (!mem->vaddr)
-		mem->vaddr = vaddr;
+	set_memory_decrypted((unsigned long)mem->vaddr, bytes >> PAGE_SHIFT);
 }
 
 static void swiotlb_init_io_tlb_mem(struct io_tlb_mem *mem, phys_addr_t start,
@@ -288,13 +252,6 @@ static void swiotlb_init_io_tlb_mem(struct io_tlb_mem *mem, phys_addr_t start,
 		mem->slots[i].alloc_size = 0;
 	}
 
-	/*
-	 * If swiotlb_unencrypted_base is set, the bounce buffer memory will
-	 * be remapped and cleared in swiotlb_update_mem_attributes.
-	 */
-	if (swiotlb_unencrypted_base)
-		return;
-
 	memset(vaddr, 0, bytes);
 	mem->vaddr = vaddr;
 	return;
-- 
1.8.3.1

[Patch v4 08/13] Drivers: hv: vmbus: Remove second mapping of VMBus monitor pages

[Michael Kelley]

With changes to how Hyper-V guest VMs flip memory between private
(encrypted) and shared (decrypted), creating a second kernel virtual
mapping for shared memory is no longer necessary.  Everything needed
for the transition to shared is handled by set_memory_decrypted().

As such, remove the code to create and manage the second
mapping for VMBus monitor pages. Because set_memory_decrypted()
and set_memory_encrypted() are no-ops in normal VMs, it's
not even necessary to test for being in a Confidential VM
(a.k.a., "Isolation VM").

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
---
 drivers/hv/connection.c   | 113 ++++++++++++----------------------------------
 drivers/hv/hyperv_vmbus.h |   2 -
 2 files changed, 28 insertions(+), 87 deletions(-)

diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index 9dc27e5..f670cfd 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -104,8 +104,14 @@ int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
 		vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
 	}
 
-	msg->monitor_page1 = vmbus_connection.monitor_pages_pa[0];
-	msg->monitor_page2 = vmbus_connection.monitor_pages_pa[1];
+	/*
+	 * shared_gpa_boundary is zero in non-SNP VMs, so it's safe to always
+	 * bitwise OR it
+	 */
+	msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]) |
+				ms_hyperv.shared_gpa_boundary;
+	msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]) |
+				ms_hyperv.shared_gpa_boundary;
 
 	msg->target_vcpu = hv_cpu_number_to_vp_number(VMBUS_CONNECT_CPU);
 
@@ -219,72 +225,27 @@ int vmbus_connect(void)
 	 * Setup the monitor notification facility. The 1st page for
 	 * parent->child and the 2nd page for child->parent
 	 */
-	vmbus_connection.monitor_pages[0] = (void *)hv_alloc_hyperv_zeroed_page();
-	vmbus_connection.monitor_pages[1] = (void *)hv_alloc_hyperv_zeroed_page();
+	vmbus_connection.monitor_pages[0] = (void *)hv_alloc_hyperv_page();
+	vmbus_connection.monitor_pages[1] = (void *)hv_alloc_hyperv_page();
 	if ((vmbus_connection.monitor_pages[0] == NULL) ||
 	    (vmbus_connection.monitor_pages[1] == NULL)) {
 		ret = -ENOMEM;
 		goto cleanup;
 	}
 
-	vmbus_connection.monitor_pages_original[0]
-		= vmbus_connection.monitor_pages[0];
-	vmbus_connection.monitor_pages_original[1]
-		= vmbus_connection.monitor_pages[1];
-	vmbus_connection.monitor_pages_pa[0]
-		= virt_to_phys(vmbus_connection.monitor_pages[0]);
-	vmbus_connection.monitor_pages_pa[1]
-		= virt_to_phys(vmbus_connection.monitor_pages[1]);
-
-	if (hv_is_isolation_supported()) {
-		ret = set_memory_decrypted((unsigned long)
-					   vmbus_connection.monitor_pages[0],
-					   1);
-		ret |= set_memory_decrypted((unsigned long)
-					    vmbus_connection.monitor_pages[1],
-					    1);
-		if (ret)
-			goto cleanup;
-
-		/*
-		 * Isolation VM with AMD SNP needs to access monitor page via
-		 * address space above shared gpa boundary.
-		 */
-		if (hv_isolation_type_snp()) {
-			vmbus_connection.monitor_pages_pa[0] +=
-				ms_hyperv.shared_gpa_boundary;
-			vmbus_connection.monitor_pages_pa[1] +=
-				ms_hyperv.shared_gpa_boundary;
-
-			vmbus_connection.monitor_pages[0]
-				= memremap(vmbus_connection.monitor_pages_pa[0],
-					   HV_HYP_PAGE_SIZE,
-					   MEMREMAP_WB);
-			if (!vmbus_connection.monitor_pages[0]) {
-				ret = -ENOMEM;
-				goto cleanup;
-			}
-
-			vmbus_connection.monitor_pages[1]
-				= memremap(vmbus_connection.monitor_pages_pa[1],
-					   HV_HYP_PAGE_SIZE,
-					   MEMREMAP_WB);
-			if (!vmbus_connection.monitor_pages[1]) {
-				ret = -ENOMEM;
-				goto cleanup;
-			}
-		}
-
-		/*
-		 * Set memory host visibility hvcall smears memory
-		 * and so zero monitor pages here.
-		 */
-		memset(vmbus_connection.monitor_pages[0], 0x00,
-		       HV_HYP_PAGE_SIZE);
-		memset(vmbus_connection.monitor_pages[1], 0x00,
-		       HV_HYP_PAGE_SIZE);
+	ret = set_memory_decrypted((unsigned long)
+				vmbus_connection.monitor_pages[0], 1);
+	ret |= set_memory_decrypted((unsigned long)
+				vmbus_connection.monitor_pages[1], 1);
+	if (ret)
+		goto cleanup;
 
-	}
+	/*
+	 * Set_memory_decrypted() will change the memory contents if
+	 * decryption occurs, so zero monitor pages here.
+	 */
+	memset(vmbus_connection.monitor_pages[0], 0x00, HV_HYP_PAGE_SIZE);
+	memset(vmbus_connection.monitor_pages[1], 0x00, HV_HYP_PAGE_SIZE);
 
 	msginfo = kzalloc(sizeof(*msginfo) +
 			  sizeof(struct vmbus_channel_initiate_contact),
@@ -376,31 +337,13 @@ void vmbus_disconnect(void)
 		vmbus_connection.int_page = NULL;
 	}
 
-	if (hv_is_isolation_supported()) {
-		/*
-		 * memunmap() checks input address is ioremap address or not
-		 * inside. It doesn't unmap any thing in the non-SNP CVM and
-		 * so not check CVM type here.
-		 */
-		memunmap(vmbus_connection.monitor_pages[0]);
-		memunmap(vmbus_connection.monitor_pages[1]);
-
-		set_memory_encrypted((unsigned long)
-			vmbus_connection.monitor_pages_original[0],
-			1);
-		set_memory_encrypted((unsigned long)
-			vmbus_connection.monitor_pages_original[1],
-			1);
-	}
+	set_memory_encrypted((unsigned long)vmbus_connection.monitor_pages[0], 1);
+	set_memory_encrypted((unsigned long)vmbus_connection.monitor_pages[1], 1);
 
-	hv_free_hyperv_page((unsigned long)
-		vmbus_connection.monitor_pages_original[0]);
-	hv_free_hyperv_page((unsigned long)
-		vmbus_connection.monitor_pages_original[1]);
-	vmbus_connection.monitor_pages_original[0] =
-		vmbus_connection.monitor_pages[0] = NULL;
-	vmbus_connection.monitor_pages_original[1] =
-		vmbus_connection.monitor_pages[1] = NULL;
+	hv_free_hyperv_page((unsigned long)vmbus_connection.monitor_pages[0]);
+	hv_free_hyperv_page((unsigned long)vmbus_connection.monitor_pages[1]);
+	vmbus_connection.monitor_pages[0] = NULL;
+	vmbus_connection.monitor_pages[1] = NULL;
 }
 
 /*
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index dc673ed..167ac51 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -241,8 +241,6 @@ struct vmbus_connection {
 	 * is child->parent notification
 	 */
 	struct hv_monitor_page *monitor_pages[2];
-	void *monitor_pages_original[2];
-	phys_addr_t monitor_pages_pa[2];
 	struct list_head chn_msg_list;
 	spinlock_t channelmsg_lock;
 
-- 
1.8.3.1

[Patch v4 09/13] Drivers: hv: vmbus: Remove second way of mapping ring buffers

[Michael Kelley]

With changes to how Hyper-V guest VMs flip memory between private
(encrypted) and shared (decrypted), it's no longer necessary to
have separate code paths for mapping VMBus ring buffers for
for normal VMs and for Confidential VMs.

As such, remove the code path that uses vmap_pfn(), and set
the protection flags argument to vmap() to account for the
difference between normal and Confidential VMs.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
---
 drivers/hv/ring_buffer.c | 62 ++++++++++++++++--------------------------------
 1 file changed, 20 insertions(+), 42 deletions(-)

diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index 57667b29..3783d9d 100644
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -186,8 +186,6 @@ int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
 		       struct page *pages, u32 page_cnt, u32 max_pkt_size)
 {
 	struct page **pages_wraparound;
-	unsigned long *pfns_wraparound;
-	u64 pfn;
 	int i;
 
 	BUILD_BUG_ON((sizeof(struct hv_ring_buffer) != PAGE_SIZE));
@@ -196,50 +194,30 @@ int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
 	 * First page holds struct hv_ring_buffer, do wraparound mapping for
 	 * the rest.
 	 */
-	if (hv_isolation_type_snp()) {
-		pfn = page_to_pfn(pages) +
-			PFN_DOWN(ms_hyperv.shared_gpa_boundary);
+	pages_wraparound = kcalloc(page_cnt * 2 - 1,
+				   sizeof(struct page *),
+				   GFP_KERNEL);
+	if (!pages_wraparound)
+		return -ENOMEM;
 
-		pfns_wraparound = kcalloc(page_cnt * 2 - 1,
-			sizeof(unsigned long), GFP_KERNEL);
-		if (!pfns_wraparound)
-			return -ENOMEM;
-
-		pfns_wraparound[0] = pfn;
-		for (i = 0; i < 2 * (page_cnt - 1); i++)
-			pfns_wraparound[i + 1] = pfn + i % (page_cnt - 1) + 1;
-
-		ring_info->ring_buffer = (struct hv_ring_buffer *)
-			vmap_pfn(pfns_wraparound, page_cnt * 2 - 1,
-				 pgprot_decrypted(PAGE_KERNEL_NOENC));
-		kfree(pfns_wraparound);
-
-		if (!ring_info->ring_buffer)
-			return -ENOMEM;
-
-		/* Zero ring buffer after setting memory host visibility. */
-		memset(ring_info->ring_buffer, 0x00, PAGE_SIZE * page_cnt);
-	} else {
-		pages_wraparound = kcalloc(page_cnt * 2 - 1,
-					   sizeof(struct page *),
-					   GFP_KERNEL);
-		if (!pages_wraparound)
-			return -ENOMEM;
-
-		pages_wraparound[0] = pages;
-		for (i = 0; i < 2 * (page_cnt - 1); i++)
-			pages_wraparound[i + 1] =
-				&pages[i % (page_cnt - 1) + 1];
+	pages_wraparound[0] = pages;
+	for (i = 0; i < 2 * (page_cnt - 1); i++)
+		pages_wraparound[i + 1] =
+			&pages[i % (page_cnt - 1) + 1];
 
-		ring_info->ring_buffer = (struct hv_ring_buffer *)
-			vmap(pages_wraparound, page_cnt * 2 - 1, VM_MAP,
-				PAGE_KERNEL);
+	ring_info->ring_buffer = (struct hv_ring_buffer *)
+		vmap(pages_wraparound, page_cnt * 2 - 1, VM_MAP,
+			pgprot_decrypted(PAGE_KERNEL_NOENC));
 
-		kfree(pages_wraparound);
-		if (!ring_info->ring_buffer)
-			return -ENOMEM;
-	}
+	kfree(pages_wraparound);
+	if (!ring_info->ring_buffer)
+		return -ENOMEM;
 
+	/*
+	 * Ensure the header page is zero'ed since
+	 * encryption status may have changed.
+	 */
+	memset(ring_info->ring_buffer, 0, HV_HYP_PAGE_SIZE);
 
 	ring_info->ring_buffer->read_index =
 		ring_info->ring_buffer->write_index = 0;
-- 
1.8.3.1

[Patch v4 10/13] hv_netvsc: Remove second mapping of send and recv buffers

[Michael Kelley]

With changes to how Hyper-V guest VMs flip memory between private
(encrypted) and shared (decrypted), creating a second kernel virtual
mapping for shared memory is no longer necessary.  Everything needed
for the transition to shared is handled by set_memory_decrypted().

As such, remove the code to create and manage the second
mapping for the pre-allocated send and recv buffers.  This mapping
is the last user of hv_map_memory()/hv_unmap_memory(), so delete
these functions as well.  Finally, hv_map_memory() is the last
user of vmap_pfn() in Hyper-V guest code, so remove the Kconfig
selection of VMAP_PFN.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
---
 arch/x86/hyperv/ivm.c           | 28 ------------------------
 drivers/hv/Kconfig              |  1 -
 drivers/hv/hv_common.c          | 11 ----------
 drivers/net/hyperv/hyperv_net.h |  2 --
 drivers/net/hyperv/netvsc.c     | 48 ++---------------------------------------
 include/asm-generic/mshyperv.h  |  2 --
 6 files changed, 2 insertions(+), 90 deletions(-)

diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index 8e2717d..83b71bd 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -356,34 +356,6 @@ void __init hv_vtom_init(void)
 
 #endif /* CONFIG_AMD_MEM_ENCRYPT */
 
-/*
- * hv_map_memory - map memory to extra space in the AMD SEV-SNP Isolation VM.
- */
-void *hv_map_memory(void *addr, unsigned long size)
-{
-	unsigned long *pfns = kcalloc(size / PAGE_SIZE,
-				      sizeof(unsigned long), GFP_KERNEL);
-	void *vaddr;
-	int i;
-
-	if (!pfns)
-		return NULL;
-
-	for (i = 0; i < size / PAGE_SIZE; i++)
-		pfns[i] = vmalloc_to_pfn(addr + i * PAGE_SIZE) +
-			(ms_hyperv.shared_gpa_boundary >> PAGE_SHIFT);
-
-	vaddr = vmap_pfn(pfns, size / PAGE_SIZE, pgprot_decrypted(PAGE_KERNEL_NOENC));
-	kfree(pfns);
-
-	return vaddr;
-}
-
-void hv_unmap_memory(void *addr)
-{
-	vunmap(addr);
-}
-
 enum hv_isolation_type hv_get_isolation_type(void)
 {
 	if (!(ms_hyperv.priv_high & HV_ISOLATION))
diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
index 0747a8f..9a074cb 100644
--- a/drivers/hv/Kconfig
+++ b/drivers/hv/Kconfig
@@ -8,7 +8,6 @@ config HYPERV
 		|| (ARM64 && !CPU_BIG_ENDIAN))
 	select PARAVIRT
 	select X86_HV_CALLBACK_VECTOR if X86
-	select VMAP_PFN
 	help
 	  Select this option to run Linux as a Hyper-V client operating
 	  system.
diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index ae68298..566735f 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -308,14 +308,3 @@ u64 __weak hv_ghcb_hypercall(u64 control, void *input, void *output, u32 input_s
 	return HV_STATUS_INVALID_PARAMETER;
 }
 EXPORT_SYMBOL_GPL(hv_ghcb_hypercall);
-
-void __weak *hv_map_memory(void *addr, unsigned long size)
-{
-	return NULL;
-}
-EXPORT_SYMBOL_GPL(hv_map_memory);
-
-void __weak hv_unmap_memory(void *addr)
-{
-}
-EXPORT_SYMBOL_GPL(hv_unmap_memory);
diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index dd5919e..33d51e3 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -1139,7 +1139,6 @@ struct netvsc_device {
 
 	/* Receive buffer allocated by us but manages by NetVSP */
 	void *recv_buf;
-	void *recv_original_buf;
 	u32 recv_buf_size; /* allocated bytes */
 	struct vmbus_gpadl recv_buf_gpadl_handle;
 	u32 recv_section_cnt;
@@ -1148,7 +1147,6 @@ struct netvsc_device {
 
 	/* Send buffer allocated by us */
 	void *send_buf;
-	void *send_original_buf;
 	u32 send_buf_size;
 	struct vmbus_gpadl send_buf_gpadl_handle;
 	u32 send_section_cnt;
diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 9352dad..661bbe6 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -154,17 +154,8 @@ static void free_netvsc_device(struct rcu_head *head)
 	int i;
 
 	kfree(nvdev->extension);
-
-	if (nvdev->recv_original_buf)
-		vfree(nvdev->recv_original_buf);
-	else
-		vfree(nvdev->recv_buf);
-
-	if (nvdev->send_original_buf)
-		vfree(nvdev->send_original_buf);
-	else
-		vfree(nvdev->send_buf);
-
+	vfree(nvdev->recv_buf);
+	vfree(nvdev->send_buf);
 	bitmap_free(nvdev->send_section_map);
 
 	for (i = 0; i < VRSS_CHANNEL_MAX; i++) {
@@ -347,7 +338,6 @@ static int netvsc_init_buf(struct hv_device *device,
 	struct nvsp_message *init_packet;
 	unsigned int buf_size;
 	int i, ret = 0;
-	void *vaddr;
 
 	/* Get receive buffer area. */
 	buf_size = device_info->recv_sections * device_info->recv_section_size;
@@ -383,17 +373,6 @@ static int netvsc_init_buf(struct hv_device *device,
 		goto cleanup;
 	}
 
-	if (hv_isolation_type_snp()) {
-		vaddr = hv_map_memory(net_device->recv_buf, buf_size);
-		if (!vaddr) {
-			ret = -ENOMEM;
-			goto cleanup;
-		}
-
-		net_device->recv_original_buf = net_device->recv_buf;
-		net_device->recv_buf = vaddr;
-	}
-
 	/* Notify the NetVsp of the gpadl handle */
 	init_packet = &net_device->channel_init_pkt;
 	memset(init_packet, 0, sizeof(struct nvsp_message));
@@ -497,17 +476,6 @@ static int netvsc_init_buf(struct hv_device *device,
 		goto cleanup;
 	}
 
-	if (hv_isolation_type_snp()) {
-		vaddr = hv_map_memory(net_device->send_buf, buf_size);
-		if (!vaddr) {
-			ret = -ENOMEM;
-			goto cleanup;
-		}
-
-		net_device->send_original_buf = net_device->send_buf;
-		net_device->send_buf = vaddr;
-	}
-
 	/* Notify the NetVsp of the gpadl handle */
 	init_packet = &net_device->channel_init_pkt;
 	memset(init_packet, 0, sizeof(struct nvsp_message));
@@ -762,12 +730,6 @@ void netvsc_device_remove(struct hv_device *device)
 		netvsc_teardown_send_gpadl(device, net_device, ndev);
 	}
 
-	if (net_device->recv_original_buf)
-		hv_unmap_memory(net_device->recv_buf);
-
-	if (net_device->send_original_buf)
-		hv_unmap_memory(net_device->send_buf);
-
 	/* Release all resources */
 	free_netvsc_device_rcu(net_device);
 }
@@ -1831,12 +1793,6 @@ struct netvsc_device *netvsc_device_add(struct hv_device *device,
 	netif_napi_del(&net_device->chan_table[0].napi);
 
 cleanup2:
-	if (net_device->recv_original_buf)
-		hv_unmap_memory(net_device->recv_buf);
-
-	if (net_device->send_original_buf)
-		hv_unmap_memory(net_device->send_buf);
-
 	free_netvsc_device(&net_device->rcu);
 
 	return ERR_PTR(ret);
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index bfb9eb9..6fabc4a 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -267,8 +267,6 @@ static inline int cpumask_to_vpset_noself(struct hv_vpset *vpset,
 void hyperv_cleanup(void);
 bool hv_query_ext_cap(u64 cap_query);
 void hv_setup_dma_ops(struct device *dev, bool coherent);
-void *hv_map_memory(void *addr, unsigned long size);
-void hv_unmap_memory(void *addr);
 #else /* CONFIG_HYPERV */
 static inline bool hv_is_hyperv_initialized(void) { return false; }
 static inline bool hv_is_hibernation_supported(void) { return false; }
-- 
1.8.3.1

[Patch v4 11/13] Drivers: hv: Don't remap addresses that are above shared_gpa_boundary

[Michael Kelley]

With the vTOM bit now treated as a protection flag and not part of
the physical address, avoid remapping physical addresses with vTOM set
since technically such addresses aren't valid.  Use ioremap_cache()
instead of memremap() to ensure that the mapping provides decrypted
access, which will correctly set the vTOM bit as a protection flag.

While this change is not required for correctness with the current
implementation of memremap(), for general code hygiene it's better to
not depend on the mapping functions doing something reasonable with
a physical address that is out-of-range.

While here, fix typos in two error messages.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
---
 arch/x86/hyperv/hv_init.c |  7 +++++--
 drivers/hv/hv.c           | 23 +++++++++++++----------
 2 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 6dbfb26..9070a78 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -63,7 +63,10 @@ static int hyperv_init_ghcb(void)
 	 * memory boundary and map it here.
 	 */
 	rdmsrl(MSR_AMD64_SEV_ES_GHCB, ghcb_gpa);
-	ghcb_va = memremap(ghcb_gpa, HV_HYP_PAGE_SIZE, MEMREMAP_WB);
+
+	/* Mask out vTOM bit. ioremap_cache() maps decrypted */
+	ghcb_gpa &= ~ms_hyperv.shared_gpa_boundary;
+	ghcb_va = (void *)ioremap_cache(ghcb_gpa, HV_HYP_PAGE_SIZE);
 	if (!ghcb_va)
 		return -ENOMEM;
 
@@ -217,7 +220,7 @@ static int hv_cpu_die(unsigned int cpu)
 	if (hv_ghcb_pg) {
 		ghcb_va = (void **)this_cpu_ptr(hv_ghcb_pg);
 		if (*ghcb_va)
-			memunmap(*ghcb_va);
+			iounmap(*ghcb_va);
 		*ghcb_va = NULL;
 	}
 
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index 4d6480d..410e6c4 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -217,11 +217,13 @@ void hv_synic_enable_regs(unsigned int cpu)
 	simp.simp_enabled = 1;
 
 	if (hv_isolation_type_snp()) {
+		/* Mask out vTOM bit. ioremap_cache() maps decrypted */
+		u64 base = (simp.base_simp_gpa << HV_HYP_PAGE_SHIFT) &
+				~ms_hyperv.shared_gpa_boundary;
 		hv_cpu->synic_message_page
-			= memremap(simp.base_simp_gpa << HV_HYP_PAGE_SHIFT,
-				   HV_HYP_PAGE_SIZE, MEMREMAP_WB);
+			= (void *)ioremap_cache(base, HV_HYP_PAGE_SIZE);
 		if (!hv_cpu->synic_message_page)
-			pr_err("Fail to map syinc message page.\n");
+			pr_err("Fail to map synic message page.\n");
 	} else {
 		simp.base_simp_gpa = virt_to_phys(hv_cpu->synic_message_page)
 			>> HV_HYP_PAGE_SHIFT;
@@ -234,12 +236,13 @@ void hv_synic_enable_regs(unsigned int cpu)
 	siefp.siefp_enabled = 1;
 
 	if (hv_isolation_type_snp()) {
-		hv_cpu->synic_event_page =
-			memremap(siefp.base_siefp_gpa << HV_HYP_PAGE_SHIFT,
-				 HV_HYP_PAGE_SIZE, MEMREMAP_WB);
-
+		/* Mask out vTOM bit. ioremap_cache() maps decrypted */
+		u64 base = (siefp.base_siefp_gpa << HV_HYP_PAGE_SHIFT) &
+				~ms_hyperv.shared_gpa_boundary;
+		hv_cpu->synic_event_page
+			= (void *)ioremap_cache(base, HV_HYP_PAGE_SIZE);
 		if (!hv_cpu->synic_event_page)
-			pr_err("Fail to map syinc event page.\n");
+			pr_err("Fail to map synic event page.\n");
 	} else {
 		siefp.base_siefp_gpa = virt_to_phys(hv_cpu->synic_event_page)
 			>> HV_HYP_PAGE_SHIFT;
@@ -316,7 +319,7 @@ void hv_synic_disable_regs(unsigned int cpu)
 	 */
 	simp.simp_enabled = 0;
 	if (hv_isolation_type_snp())
-		memunmap(hv_cpu->synic_message_page);
+		iounmap(hv_cpu->synic_message_page);
 	else
 		simp.base_simp_gpa = 0;
 
@@ -326,7 +329,7 @@ void hv_synic_disable_regs(unsigned int cpu)
 	siefp.siefp_enabled = 0;
 
 	if (hv_isolation_type_snp())
-		memunmap(hv_cpu->synic_event_page);
+		iounmap(hv_cpu->synic_event_page);
 	else
 		siefp.base_siefp_gpa = 0;
 
-- 
1.8.3.1

[Patch v4 12/13] PCI: hv: Add hypercalls to read/write MMIO space

[Michael Kelley]

To support PCI pass-thru devices in Confidential VMs, Hyper-V
has added hypercalls to read and write MMIO space. Add the
appropriate definitions to hyperv-tlfs.h and implement
functions to make the hypercalls. These functions are used
in a subsequent patch.

Co-developed-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
---
 arch/x86/include/asm/hyperv-tlfs.h  |  3 ++
 drivers/pci/controller/pci-hyperv.c | 64 +++++++++++++++++++++++++++++++++++++
 include/asm-generic/hyperv-tlfs.h   | 22 +++++++++++++
 3 files changed, 89 insertions(+)

diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index 6d9368e..4d67c38 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -117,6 +117,9 @@
 /* Recommend using enlightened VMCS */
 #define HV_X64_ENLIGHTENED_VMCS_RECOMMENDED		BIT(14)
 
+/* Use hypercalls for MMIO config space access */
+#define HV_X64_USE_MMIO_HYPERCALLS			BIT(21)
+
 /*
  * CPU management features identification.
  * These are HYPERV_CPUID_CPU_MANAGEMENT_FEATURES.EAX bits.
diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 084f531..bbe6e36 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -1041,6 +1041,70 @@ static int wslot_to_devfn(u32 wslot)
 	return PCI_DEVFN(slot_no.bits.dev, slot_no.bits.func);
 }
 
+static void hv_pci_read_mmio(struct device *dev, phys_addr_t gpa, int size, u32 *val)
+{
+	struct hv_mmio_read_input *in;
+	struct hv_mmio_read_output *out;
+	u64 ret;
+
+	/*
+	 * Must be called with interrupts disabled so it is safe
+	 * to use the per-cpu input argument page.  Use it for
+	 * both input and output.
+	 */
+	in = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	out = *this_cpu_ptr(hyperv_pcpu_input_arg) + sizeof(*in);
+	in->gpa = gpa;
+	in->size = size;
+
+	ret = hv_do_hypercall(HVCALL_MMIO_READ, in, out);
+	if (hv_result_success(ret)) {
+		switch (size) {
+		case 1:
+			*val = *(u8 *)(out->data);
+			break;
+		case 2:
+			*val = *(u16 *)(out->data);
+			break;
+		default:
+			*val = *(u32 *)(out->data);
+			break;
+		}
+	} else
+		dev_err(dev, "MMIO read hypercall error %llx addr %llx size %d\n",
+				ret, gpa, size);
+}
+
+static void hv_pci_write_mmio(struct device *dev, phys_addr_t gpa, int size, u32 val)
+{
+	struct hv_mmio_write_input *in;
+	u64 ret;
+
+	/*
+	 * Must be called with interrupts disabled so it is safe
+	 * to use the per-cpu input argument memory.
+	 */
+	in = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	in->gpa = gpa;
+	in->size = size;
+	switch (size) {
+	case 1:
+		*(u8 *)(in->data) = val;
+		break;
+	case 2:
+		*(u16 *)(in->data) = val;
+		break;
+	default:
+		*(u32 *)(in->data) = val;
+		break;
+	}
+
+	ret = hv_do_hypercall(HVCALL_MMIO_WRITE, in, NULL);
+	if (!hv_result_success(ret))
+		dev_err(dev, "MMIO write hypercall error %llx addr %llx size %d\n",
+				ret, gpa, size);
+}
+
 /*
  * PCI Configuration Space for these root PCI buses is implemented as a pair
  * of pages in memory-mapped I/O space.  Writing to the first page chooses
diff --git a/include/asm-generic/hyperv-tlfs.h b/include/asm-generic/hyperv-tlfs.h
index b17c6ee..fcab07b 100644
--- a/include/asm-generic/hyperv-tlfs.h
+++ b/include/asm-generic/hyperv-tlfs.h
@@ -168,6 +168,8 @@ struct ms_hyperv_tsc_page {
 #define HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_SPACE 0x00af
 #define HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_LIST 0x00b0
 #define HVCALL_MODIFY_SPARSE_GPA_PAGE_HOST_VISIBILITY 0x00db
+#define HVCALL_MMIO_READ			0x0106
+#define HVCALL_MMIO_WRITE			0x0107
 
 /* Extended hypercalls */
 #define HV_EXT_CALL_QUERY_CAPABILITIES		0x8001
@@ -790,4 +792,24 @@ struct hv_memory_hint {
 	union hv_gpa_page_range ranges[];
 } __packed;
 
+/* Data structures for HVCALL_MMIO_READ and HVCALL_MMIO_WRITE */
+#define HV_HYPERCALL_MMIO_MAX_DATA_LENGTH 64
+
+struct hv_mmio_read_input {
+	u64 gpa;
+	u32 size;
+	u32 reserved;
+} __packed;
+
+struct hv_mmio_read_output {
+	u8 data[HV_HYPERCALL_MMIO_MAX_DATA_LENGTH];
+} __packed;
+
+struct hv_mmio_write_input {
+	u64 gpa;
+	u32 size;
+	u32 reserved;
+	u8 data[HV_HYPERCALL_MMIO_MAX_DATA_LENGTH];
+} __packed;
+
 #endif
-- 
1.8.3.1

[Patch v4 13/13] PCI: hv: Enable PCI pass-thru devices in Confidential VMs

[Michael Kelley]

For PCI pass-thru devices in a Confidential VM, Hyper-V requires
that PCI config space be accessed via hypercalls.  In normal VMs,
config space accesses are trapped to the Hyper-V host and emulated.
But in a confidential VM, the host can't access guest memory to
decode the instruction for emulation, so an explicit hypercall must
be used.

Update the PCI config space access functions to use the hypercalls
when such use is indicated by Hyper-V flags.  Also, set the flag to
allow the Hyper-V PCI driver to be loaded and used in a Confidential
VM (a.k.a., "Isolation VM").  The driver has previously been hardened
against a malicious Hyper-V host[1].

[1] https://lore.kernel.org/all/20220511223207.3386-2-parri.andrea@gmail.com/

Co-developed-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
---
 drivers/hv/channel_mgmt.c           |   2 +-
 drivers/pci/controller/pci-hyperv.c | 168 ++++++++++++++++++++++--------------
 2 files changed, 105 insertions(+), 65 deletions(-)

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index cc23b90..007f26d 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -67,7 +67,7 @@
 	{ .dev_type = HV_PCIE,
 	  HV_PCIE_GUID,
 	  .perf_device = false,
-	  .allowed_in_isolated = false,
+	  .allowed_in_isolated = true,
 	},
 
 	/* Synthetic Frame Buffer */
diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index bbe6e36..f874f89 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -514,6 +514,7 @@ struct hv_pcibus_device {
 
 	/* Highest slot of child device with resources allocated */
 	int wslot_res_allocated;
+	bool use_calls; /* Use hypercalls to access mmio cfg space */
 
 	/* hypercall arg, must not cross page boundary */
 	struct hv_retarget_device_interrupt retarget_msi_interrupt_params;
@@ -1123,8 +1124,10 @@ static void hv_pci_write_mmio(struct device *dev, phys_addr_t gpa, int size, u32
 static void _hv_pcifront_read_config(struct hv_pci_dev *hpdev, int where,
 				     int size, u32 *val)
 {
+	struct hv_pcibus_device *hbus = hpdev->hbus;
+	struct device *dev = &hbus->hdev->device;
+	int offset = where + CFG_PAGE_OFFSET;
 	unsigned long flags;
-	void __iomem *addr = hpdev->hbus->cfg_addr + CFG_PAGE_OFFSET + where;
 
 	/*
 	 * If the attempt is to read the IDs or the ROM BAR, simulate that.
@@ -1152,56 +1155,79 @@ static void _hv_pcifront_read_config(struct hv_pci_dev *hpdev, int where,
 		 */
 		*val = 0;
 	} else if (where + size <= CFG_PAGE_SIZE) {
-		spin_lock_irqsave(&hpdev->hbus->config_lock, flags);
-		/* Choose the function to be read. (See comment above) */
-		writel(hpdev->desc.win_slot.slot, hpdev->hbus->cfg_addr);
-		/* Make sure the function was chosen before we start reading. */
-		mb();
-		/* Read from that function's config space. */
-		switch (size) {
-		case 1:
-			*val = readb(addr);
-			break;
-		case 2:
-			*val = readw(addr);
-			break;
-		default:
-			*val = readl(addr);
-			break;
+
+		spin_lock_irqsave(&hbus->config_lock, flags);
+		if (hbus->use_calls) {
+			phys_addr_t addr = hbus->mem_config->start + offset;
+
+			hv_pci_write_mmio(dev, hbus->mem_config->start, 4,
+						hpdev->desc.win_slot.slot);
+			hv_pci_read_mmio(dev, addr, size, val);
+		} else {
+			void __iomem *addr = hbus->cfg_addr + offset;
+
+			/* Choose the function to be read. (See comment above) */
+			writel(hpdev->desc.win_slot.slot, hbus->cfg_addr);
+			/* Make sure the function was chosen before reading. */
+			mb();
+			/* Read from that function's config space. */
+			switch (size) {
+			case 1:
+				*val = readb(addr);
+				break;
+			case 2:
+				*val = readw(addr);
+				break;
+			default:
+				*val = readl(addr);
+				break;
+			}
+			/*
+			 * Make sure the read was done before we release the
+			 * spinlock allowing consecutive reads/writes.
+			 */
+			mb();
 		}
-		/*
-		 * Make sure the read was done before we release the spinlock
-		 * allowing consecutive reads/writes.
-		 */
-		mb();
-		spin_unlock_irqrestore(&hpdev->hbus->config_lock, flags);
+		spin_unlock_irqrestore(&hbus->config_lock, flags);
 	} else {
-		dev_err(&hpdev->hbus->hdev->device,
-			"Attempt to read beyond a function's config space.\n");
+		dev_err(dev, "Attempt to read beyond a function's config space.\n");
 	}
 }
 
 static u16 hv_pcifront_get_vendor_id(struct hv_pci_dev *hpdev)
 {
+	struct hv_pcibus_device *hbus = hpdev->hbus;
+	struct device *dev = &hbus->hdev->device;
+	u32 val;
 	u16 ret;
 	unsigned long flags;
-	void __iomem *addr = hpdev->hbus->cfg_addr + CFG_PAGE_OFFSET +
-			     PCI_VENDOR_ID;
 
-	spin_lock_irqsave(&hpdev->hbus->config_lock, flags);
+	spin_lock_irqsave(&hbus->config_lock, flags);
 
-	/* Choose the function to be read. (See comment above) */
-	writel(hpdev->desc.win_slot.slot, hpdev->hbus->cfg_addr);
-	/* Make sure the function was chosen before we start reading. */
-	mb();
-	/* Read from that function's config space. */
-	ret = readw(addr);
-	/*
-	 * mb() is not required here, because the spin_unlock_irqrestore()
-	 * is a barrier.
-	 */
+	if (hbus->use_calls) {
+		phys_addr_t addr = hbus->mem_config->start +
+					 CFG_PAGE_OFFSET + PCI_VENDOR_ID;
+
+		hv_pci_write_mmio(dev, hbus->mem_config->start, 4,
+					hpdev->desc.win_slot.slot);
+		hv_pci_read_mmio(dev, addr, 2, &val);
+		ret = val;  /* Truncates to 16 bits */
+	} else {
+		void __iomem *addr = hbus->cfg_addr + CFG_PAGE_OFFSET +
+					     PCI_VENDOR_ID;
+		/* Choose the function to be read. (See comment above) */
+		writel(hpdev->desc.win_slot.slot, hbus->cfg_addr);
+		/* Make sure the function was chosen before we start reading. */
+		mb();
+		/* Read from that function's config space. */
+		ret = readw(addr);
+		/*
+		 * mb() is not required here, because the
+		 * spin_unlock_irqrestore() is a barrier.
+		 */
+	}
 
-	spin_unlock_irqrestore(&hpdev->hbus->config_lock, flags);
+	spin_unlock_irqrestore(&hbus->config_lock, flags);
 
 	return ret;
 }
@@ -1216,39 +1242,51 @@ static u16 hv_pcifront_get_vendor_id(struct hv_pci_dev *hpdev)
 static void _hv_pcifront_write_config(struct hv_pci_dev *hpdev, int where,
 				      int size, u32 val)
 {
+	struct hv_pcibus_device *hbus = hpdev->hbus;
+	struct device *dev = &hbus->hdev->device;
+	int offset = where + CFG_PAGE_OFFSET;
 	unsigned long flags;
-	void __iomem *addr = hpdev->hbus->cfg_addr + CFG_PAGE_OFFSET + where;
 
 	if (where >= PCI_SUBSYSTEM_VENDOR_ID &&
 	    where + size <= PCI_CAPABILITY_LIST) {
 		/* SSIDs and ROM BARs are read-only */
 	} else if (where >= PCI_COMMAND && where + size <= CFG_PAGE_SIZE) {
-		spin_lock_irqsave(&hpdev->hbus->config_lock, flags);
-		/* Choose the function to be written. (See comment above) */
-		writel(hpdev->desc.win_slot.slot, hpdev->hbus->cfg_addr);
-		/* Make sure the function was chosen before we start writing. */
-		wmb();
-		/* Write to that function's config space. */
-		switch (size) {
-		case 1:
-			writeb(val, addr);
-			break;
-		case 2:
-			writew(val, addr);
-			break;
-		default:
-			writel(val, addr);
-			break;
+		spin_lock_irqsave(&hbus->config_lock, flags);
+
+		if (hbus->use_calls) {
+			phys_addr_t addr = hbus->mem_config->start + offset;
+
+			hv_pci_write_mmio(dev, hbus->mem_config->start, 4,
+						hpdev->desc.win_slot.slot);
+			hv_pci_write_mmio(dev, addr, size, val);
+		} else {
+			void __iomem *addr = hbus->cfg_addr + offset;
+
+			/* Choose the function to write. (See comment above) */
+			writel(hpdev->desc.win_slot.slot, hbus->cfg_addr);
+			/* Make sure the function was chosen before writing. */
+			wmb();
+			/* Write to that function's config space. */
+			switch (size) {
+			case 1:
+				writeb(val, addr);
+				break;
+			case 2:
+				writew(val, addr);
+				break;
+			default:
+				writel(val, addr);
+				break;
+			}
+			/*
+			 * Make sure the write was done before we release the
+			 * spinlock allowing consecutive reads/writes.
+			 */
+			mb();
 		}
-		/*
-		 * Make sure the write was done before we release the spinlock
-		 * allowing consecutive reads/writes.
-		 */
-		mb();
-		spin_unlock_irqrestore(&hpdev->hbus->config_lock, flags);
+		spin_unlock_irqrestore(&hbus->config_lock, flags);
 	} else {
-		dev_err(&hpdev->hbus->hdev->device,
-			"Attempt to write beyond a function's config space.\n");
+		dev_err(dev, "Attempt to write beyond a function's config space.\n");
 	}
 }
 
@@ -3627,6 +3665,7 @@ static int hv_pci_probe(struct hv_device *hdev,
 	hbus->bridge->domain_nr = dom;
 #ifdef CONFIG_X86
 	hbus->sysdata.domain = dom;
+	hbus->use_calls = !!(ms_hyperv.hints & HV_X64_USE_MMIO_HYPERCALLS);
 #elif defined(CONFIG_ARM64)
 	/*
 	 * Set the PCI bus parent to be the corresponding VMbus
@@ -3636,6 +3675,7 @@ static int hv_pci_probe(struct hv_device *hdev,
 	 * information to devices created on the bus.
 	 */
 	hbus->sysdata.parent = hdev->device.parent;
+	hbus->use_calls = false;
 #endif
 
 	hbus->hdev = hdev;
-- 
1.8.3.1

Re: [Patch v4 01/13] x86/ioapic: Gate decrypted mapping on cc_platform_has() attribute

[Borislav Petkov]

On Thu, Dec 01, 2022 at 07:30:19PM -0800, Michael Kelley wrote:
> Current code always maps the IO-APIC as shared (decrypted) in a
> confidential VM. But Hyper-V guest VMs on AMD SEV-SNP with vTOM
> enabled use a paravisor running in VMPL0 to emulate the IO-APIC.
> In such a case, the IO-APIC must be accessed as private (encrypted).

Lemme see I understand this correctly:

the paravisor is emulating the IO-APIC in the lower range of the address
space, under the vTOM which is accessed encrypted.

That's why you need to access it encrypted in the guest.

Close?

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

Re: [Patch v4 01/13] x86/ioapic: Gate decrypted mapping on cc_platform_has() attribute

[Sathyanarayanan Kuppuswamy]

On 12/1/22 7:30 PM, Michael Kelley wrote:
> Current code always maps the IO-APIC as shared (decrypted) in a
> confidential VM. But Hyper-V guest VMs on AMD SEV-SNP with vTOM
> enabled use a paravisor running in VMPL0 to emulate the IO-APIC.
> In such a case, the IO-APIC must be accessed as private (encrypted).
> 
> Fix this by gating the IO-APIC decrypted mapping on a new
> cc_platform_has() attribute that a subsequent patch in the series
> will set only for guests using vTOM.
> 
> Signed-off-by: Michael Kelley <mikelley@microsoft.com>
> Reviewed-by: Wei Liu <wei.liu@kernel.org>
> ---

Looks good to me.

Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>

>  arch/x86/kernel/apic/io_apic.c |  3 ++-
>  include/linux/cc_platform.h    | 12 ++++++++++++
>  2 files changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
> index a868b76..2b70e2e 100644
> --- a/arch/x86/kernel/apic/io_apic.c
> +++ b/arch/x86/kernel/apic/io_apic.c
> @@ -2686,7 +2686,8 @@ static void io_apic_set_fixmap(enum fixed_addresses idx, phys_addr_t phys)
>  	 * Ensure fixmaps for IOAPIC MMIO respect memory encryption pgprot
>  	 * bits, just like normal ioremap():
>  	 */
> -	flags = pgprot_decrypted(flags);
> +	if (!cc_platform_has(CC_ATTR_ACCESS_IOAPIC_ENCRYPTED))
> +		flags = pgprot_decrypted(flags);
>  
>  	__set_fixmap(idx, phys, flags);
>  }
> diff --git a/include/linux/cc_platform.h b/include/linux/cc_platform.h
> index cb0d6cd..7b63a7d 100644
> --- a/include/linux/cc_platform.h
> +++ b/include/linux/cc_platform.h
> @@ -90,6 +90,18 @@ enum cc_attr {
>  	 * Examples include TDX Guest.
>  	 */
>  	CC_ATTR_HOTPLUG_DISABLED,
> +
> +	/**
> +	 * @CC_ATTR_ACCESS_IOAPIC_ENCRYPTED: Guest VM IO-APIC is encrypted
> +	 *
> +	 * The platform/OS is running as a guest/virtual machine with
> +	 * an IO-APIC that is emulated by a paravisor running in the
> +	 * guest VM context. As such, the IO-APIC is accessed in the
> +	 * encrypted portion of the guest physical address space.
> +	 *
> +	 * Examples include Hyper-V SEV-SNP guests using vTOM.
> +	 */
> +	CC_ATTR_ACCESS_IOAPIC_ENCRYPTED,
>  };
>  
>  #ifdef CONFIG_ARCH_HAS_CC_PLATFORM

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer

Re: [Patch v4 05/13] init: Call mem_encrypt_init() after Hyper-V hypercall init is done

[Sathyanarayanan Kuppuswamy]

On 12/1/22 7:30 PM, Michael Kelley wrote:
> Full Hyper-V initialization, including support for hypercalls, is done
> as an apic_post_init callback via late_time_init().  mem_encrypt_init()
> needs to make hypercalls when it marks swiotlb memory as decrypted.
> But mem_encrypt_init() is currently called a few lines before
> late_time_init(), so the hypercalls don't work.

Did you consider moving hyper-v hypercall initialization before
 mem_encrypt_init(). Is there any dependency issue?

> 
> Fix this by moving mem_encrypt_init() after late_time_init() and
> related clock initializations. The intervening initializations don't
> do any I/O that requires the swiotlb, so moving mem_encrypt_init()
> slightly later has no impact.
> 
> Signed-off-by: Michael Kelley <mikelley@microsoft.com>
> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
> ---
>  init/main.c | 19 +++++++++++--------
>  1 file changed, 11 insertions(+), 8 deletions(-)
> 
> diff --git a/init/main.c b/init/main.c
> index e1c3911..5a7c466 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -1088,14 +1088,6 @@ asmlinkage __visible void __init __no_sanitize_address start_kernel(void)
>  	 */
>  	locking_selftest();
>  
> -	/*
> -	 * This needs to be called before any devices perform DMA
> -	 * operations that might use the SWIOTLB bounce buffers. It will
> -	 * mark the bounce buffers as decrypted so that their usage will
> -	 * not cause "plain-text" data to be decrypted when accessed.
> -	 */
> -	mem_encrypt_init();
> -
>  #ifdef CONFIG_BLK_DEV_INITRD
>  	if (initrd_start && !initrd_below_start_ok &&
>  	    page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
> @@ -1112,6 +1104,17 @@ asmlinkage __visible void __init __no_sanitize_address start_kernel(void)
>  		late_time_init();
>  	sched_clock_init();
>  	calibrate_delay();
> +
> +	/*
> +	 * This needs to be called before any devices perform DMA
> +	 * operations that might use the SWIOTLB bounce buffers. It will
> +	 * mark the bounce buffers as decrypted so that their usage will
> +	 * not cause "plain-text" data to be decrypted when accessed. It
> +	 * must be called after late_time_init() so that Hyper-V x86/x64
> +	 * hypercalls work when the SWIOTLB bounce buffers are decrypted.
> +	 */
> +	mem_encrypt_init();
> +
>  	pid_idr_init();
>  	anon_vma_init();
>  #ifdef CONFIG_X86

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer

RE: [Patch v4 01/13] x86/ioapic: Gate decrypted mapping on cc_platform_has() attribute

[Michael Kelley (LINUX)]

From: Borislav Petkov <bp@alien8.de> Sent: Tuesday, December 6, 2022 11:23 AM
> 
> On Thu, Dec 01, 2022 at 07:30:19PM -0800, Michael Kelley wrote:
> > Current code always maps the IO-APIC as shared (decrypted) in a
> > confidential VM. But Hyper-V guest VMs on AMD SEV-SNP with vTOM
> > enabled use a paravisor running in VMPL0 to emulate the IO-APIC.
> > In such a case, the IO-APIC must be accessed as private (encrypted).
> 
> Lemme see I understand this correctly:
> 
> the paravisor is emulating the IO-APIC in the lower range of the address
> space, under the vTOM which is accessed encrypted.
> 
> That's why you need to access it encrypted in the guest.
> 
> Close?
> 

Exactly correct.

Michael

RE: [Patch v4 05/13] init: Call mem_encrypt_init() after Hyper-V hypercall init is done

[Michael Kelley (LINUX)]

From: Sathyanarayanan Kuppuswamy <sathyanarayanan.kuppuswamy@linux.intel.com>
> 
> 
> 
> On 12/1/22 7:30 PM, Michael Kelley wrote:
> > Full Hyper-V initialization, including support for hypercalls, is done
> > as an apic_post_init callback via late_time_init().  mem_encrypt_init()
> > needs to make hypercalls when it marks swiotlb memory as decrypted.
> > But mem_encrypt_init() is currently called a few lines before
> > late_time_init(), so the hypercalls don't work.
> 
> Did you consider moving hyper-v hypercall initialization before
>  mem_encrypt_init(). Is there any dependency issue?

Hyper-V initialization has historically been done using the callbacks
that exist in the x86 initialization paths, rather than adding explicit
Hyper-V init calls.  As noted above, the full Hyper-V init is done on
the apic_post_init callback via late_time_init().  Conceivably we could
add an explicit call to do the Hyper-V init, but I think there's still a
problem in putting that Hyper-V init prior to the current location of
mem_encrypt_init().  I'd have to go check the history, but I think the
Hyper-V init needs to happen after the APIC is initialized.

It seems like moving mem_encrypt_init() slightly later is the cleaner
long-term solution.  Are you aware of a likely problem arising in the
future with moving mem_encrypt_init()?

Michael

> 
> >
> > Fix this by moving mem_encrypt_init() after late_time_init() and
> > related clock initializations. The intervening initializations don't
> > do any I/O that requires the swiotlb, so moving mem_encrypt_init()
> > slightly later has no impact.
> >

Re: [Patch v4 05/13] init: Call mem_encrypt_init() after Hyper-V hypercall init is done

[Sathyanarayanan Kuppuswamy]

On 12/6/22 12:13 PM, Michael Kelley (LINUX) wrote:
> From: Sathyanarayanan Kuppuswamy <sathyanarayanan.kuppuswamy@linux.intel.com>
>>
>>
>>
>> On 12/1/22 7:30 PM, Michael Kelley wrote:
>>> Full Hyper-V initialization, including support for hypercalls, is done
>>> as an apic_post_init callback via late_time_init().  mem_encrypt_init()
>>> needs to make hypercalls when it marks swiotlb memory as decrypted.
>>> But mem_encrypt_init() is currently called a few lines before
>>> late_time_init(), so the hypercalls don't work.
>>
>> Did you consider moving hyper-v hypercall initialization before
>>  mem_encrypt_init(). Is there any dependency issue?
> 
> Hyper-V initialization has historically been done using the callbacks
> that exist in the x86 initialization paths, rather than adding explicit
> Hyper-V init calls.  As noted above, the full Hyper-V init is done on
> the apic_post_init callback via late_time_init().  Conceivably we could
> add an explicit call to do the Hyper-V init, but I think there's still a
> problem in putting that Hyper-V init prior to the current location of
> mem_encrypt_init().  I'd have to go check the history, but I think the
> Hyper-V init needs to happen after the APIC is initialized.

Ok. If there is a dependency or complexity issue, I recommend adding that
detail in the commit log.

> 
> It seems like moving mem_encrypt_init() slightly later is the cleaner
> long-term solution.  Are you aware of a likely problem arising in the
> future with moving mem_encrypt_init()?

I did not investigate in depth, but there appears to be no problem with
moving mem_encrypt_init(). But my point is, if it is possible to fix this
easily by changing Hyper-v specific initialization, we should consider it
first before considering moving the common mem_encrypt_init() function.



> 
> Michael
> 
>>
>>>
>>> Fix this by moving mem_encrypt_init() after late_time_init() and
>>> related clock initializations. The intervening initializations don't
>>> do any I/O that requires the swiotlb, so moving mem_encrypt_init()
>>> slightly later has no impact.
>>>

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer

Re: [Patch v4 01/13] x86/ioapic: Gate decrypted mapping on cc_platform_has() attribute

[Borislav Petkov]

On Tue, Dec 06, 2022 at 07:54:02PM +0000, Michael Kelley (LINUX) wrote:
> Exactly correct.

Ok, thanks.

Let's put that in the commit message and get rid of the "subsequent
patch" wording as patch order in git is ambiguous.

IOW, something like this:

    Current code always maps the IO-APIC as shared (decrypted) in a
    confidential VM. But Hyper-V guest VMs on AMD SEV-SNP with vTOM enabled
    use a paravisor running in VMPL0 to emulate the IO-APIC.

    In such a case, the IO-APIC must be accessed as private (encrypted)
    because the paravisor emulates the IO-APIC in the lower half of the vTOM
    where all accesses must be encrypted.

    Add a new CC attribute which determines how the IO-APIC MMIO mapping
    should be established depending on the platform the kernel is running on
    as a guest.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

Re: [Patch v4 03/13] Drivers: hv: Explicitly request decrypted in vmap_pfn() calls

[Borislav Petkov]

On Thu, Dec 01, 2022 at 07:30:21PM -0800, Michael Kelley wrote:
> In preparation for a subsequent patch,

Yeah, once those are all in git, the concept of "subsequent patch"
becomes ambiguous depending on how you're sorting them. So try to read
that commit message out of the context of all those "subsequent patches"
and see if it still makes sense.

IOW, you should strive for your commit messages to make sense on their
own, without referencing other patches. If possible, that is.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

Re: [Patch v4 04/13] x86/mm: Handle decryption/re-encryption of bss_decrypted consistently

[Borislav Petkov]

On Thu, Dec 01, 2022 at 07:30:22PM -0800, Michael Kelley wrote:
> Current code in sme_postprocess_startup() decrypts the bss_decrypted
> section when sme_me_mask is non-zero.  But code in
> mem_encrypt_free_decrypted_mem() re-encrypts the unused portion based
> on CC_ATTR_MEM_ENCRYPT.  In a Hyper-V guest VM using vTOM, these
> conditions are not equivalent as sme_me_mask is always zero when
> using vTOM.  Consequently, mem_encrypt_free_decrypted_mem() attempts
> to re-encrypt memory that was never decrypted.
> 
> Fix this in mem_encrypt_free_decrypted_mem() by conditioning the
> re-encryption on the same test for non-zero sme_me_mask.  Hyper-V
> guests using vTOM don't need the bss_decrypted section to be
> decrypted, so skipping the decryption/re-encryption doesn't cause
> a problem.

Lemme simplify the formulations a bit:

"sme_postprocess_startup() decrypts the bss_decrypted ection when me_mask
sme_is non-zero.

mem_encrypt_free_decrypted_mem() re-encrypts the unused portion based on
CC_ATTR_MEM_ENCRYPT.

In a Hyper-V guest VM using vTOM, these conditions are not equivalent
as sme_me_mask is always zero when using vTOM. Consequently,
mem_encrypt_free_decrypted_mem() attempts to re-encrypt memory that was
never decrypted.

So check sme_me_mask in mem_encrypt_free_decrypted_mem() too.

Hyper-V guests using vTOM don't need the bss_decrypted section to be
decrypted, so skipping the decryption/re-encryption doesn't cause a
problem."

> Fixes: e9d1d2bb75b2 ("treewide: Replace the use of mem_encrypt_active() with cc_platform_has()")

So when you say Fixes - this is an issue only for vTOM-using VMs and
before yours, there were none. And yours needs more enablement than just
this patch.

So does this one really need to be backported to stable@?

I'm asking because there's AI which will pick it up based on this Fixes
tag up but that AI is still not that smart to replace us all. :-)

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

RE: [Patch v4 01/13] x86/ioapic: Gate decrypted mapping on cc_platform_has() attribute

[Michael Kelley (LINUX)]

From: Borislav Petkov <bp@alien8.de> Sent: Thursday, December 29, 2022 3:39 AM
> 
> On Tue, Dec 06, 2022 at 07:54:02PM +0000, Michael Kelley (LINUX) wrote:
> > Exactly correct.
> 
> Ok, thanks.
> 
> Let's put that in the commit message and get rid of the "subsequent
> patch" wording as patch order in git is ambiguous.
> 
> IOW, something like this:
> 
>     Current code always maps the IO-APIC as shared (decrypted) in a
>     confidential VM. But Hyper-V guest VMs on AMD SEV-SNP with vTOM enabled
>     use a paravisor running in VMPL0 to emulate the IO-APIC.
> 
>     In such a case, the IO-APIC must be accessed as private (encrypted)
>     because the paravisor emulates the IO-APIC in the lower half of the vTOM
>     where all accesses must be encrypted.
> 
>     Add a new CC attribute which determines how the IO-APIC MMIO mapping
>     should be established depending on the platform the kernel is running on
>     as a guest.
>
 
Works for me.  I'll adopt this wording in v5.

Michael

RE: [Patch v4 04/13] x86/mm: Handle decryption/re-encryption of bss_decrypted consistently

[Michael Kelley (LINUX)]

From: Borislav Petkov <bp@alien8.de> Sent: Thursday, December 29, 2022 4:18 AM
> 
> On Thu, Dec 01, 2022 at 07:30:22PM -0800, Michael Kelley wrote:
> > Current code in sme_postprocess_startup() decrypts the bss_decrypted
> > section when sme_me_mask is non-zero.  But code in
> > mem_encrypt_free_decrypted_mem() re-encrypts the unused portion based
> > on CC_ATTR_MEM_ENCRYPT.  In a Hyper-V guest VM using vTOM, these
> > conditions are not equivalent as sme_me_mask is always zero when
> > using vTOM.  Consequently, mem_encrypt_free_decrypted_mem() attempts
> > to re-encrypt memory that was never decrypted.
> >
> > Fix this in mem_encrypt_free_decrypted_mem() by conditioning the
> > re-encryption on the same test for non-zero sme_me_mask.  Hyper-V
> > guests using vTOM don't need the bss_decrypted section to be
> > decrypted, so skipping the decryption/re-encryption doesn't cause
> > a problem.
> 
> Lemme simplify the formulations a bit:
> 
> "sme_postprocess_startup() decrypts the bss_decrypted ection when me_mask
> sme_is non-zero.
> 
> mem_encrypt_free_decrypted_mem() re-encrypts the unused portion based on
> CC_ATTR_MEM_ENCRYPT.
> 
> In a Hyper-V guest VM using vTOM, these conditions are not equivalent
> as sme_me_mask is always zero when using vTOM. Consequently,
> mem_encrypt_free_decrypted_mem() attempts to re-encrypt memory that was
> never decrypted.
> 
> So check sme_me_mask in mem_encrypt_free_decrypted_mem() too.
> 
> Hyper-V guests using vTOM don't need the bss_decrypted section to be
> decrypted, so skipping the decryption/re-encryption doesn't cause a
> problem."

Work for me.  I'll pick up the new wording in v5.

> 
> > Fixes: e9d1d2bb75b2 ("treewide: Replace the use of mem_encrypt_active() with
> cc_platform_has()")
> 
> So when you say Fixes - this is an issue only for vTOM-using VMs and
> before yours, there were none. And yours needs more enablement than just
> this patch.
> 
> So does this one really need to be backported to stable@?
> 
> I'm asking because there's AI which will pick it up based on this Fixes
> tag up but that AI is still not that smart to replace us all. :-)
> 

I'm ambivalent on the backport to stable.  One might argue that older
kernel versions are conceptually wrong in using different conditions for
the decryption and re-encryption.  But as you said, they aren't broken
from a practical standpoint because sme_me_mask and
CC_ATTR_MEM_ENCRYPT are equivalent prior to my patch set.  However,
the email thread with Sathyanarayanan Kuppuswamy, Tom Lendacky,
and Dexuan Cui concluded that a Fixes: tag is appropriate.   See
https://lore.kernel.org/lkml/fbf2cdcc-4ff7-b466-a6af-7a147f3bc94d@amd.com/
and
https://lore.kernel.org/lkml/BYAPR21MB1688A31ED795ED1B5ACB6D26D7099@BYAPR21MB1688.namprd21.prod.outlook.com/

Michael

Re: [Patch v4 04/13] x86/mm: Handle decryption/re-encryption of bss_decrypted consistently

[Bjorn Helgaas]

On Thu, Dec 29, 2022 at 01:17:48PM +0100, Borislav Petkov wrote:
> On Thu, Dec 01, 2022 at 07:30:22PM -0800, Michael Kelley wrote:
> > Current code in sme_postprocess_startup() decrypts the bss_decrypted
> > section when sme_me_mask is non-zero.  But code in
> > mem_encrypt_free_decrypted_mem() re-encrypts the unused portion based
> > on CC_ATTR_MEM_ENCRYPT.  In a Hyper-V guest VM using vTOM, these
> > conditions are not equivalent as sme_me_mask is always zero when
> > using vTOM.  Consequently, mem_encrypt_free_decrypted_mem() attempts
> > to re-encrypt memory that was never decrypted.
> > 
> > Fix this in mem_encrypt_free_decrypted_mem() by conditioning the
> > re-encryption on the same test for non-zero sme_me_mask.  Hyper-V
> > guests using vTOM don't need the bss_decrypted section to be
> > decrypted, so skipping the decryption/re-encryption doesn't cause
> > a problem.
> 
> Lemme simplify the formulations a bit:
> 
> "sme_postprocess_startup() decrypts the bss_decrypted ection when me_mask
> sme_is non-zero.

s/ection/section/

(In case you copy/paste this text without noticing the typo)

Re: [Patch v4 04/13] x86/mm: Handle decryption/re-encryption of bss_decrypted consistently

[Borislav Petkov]

On Thu, Dec 29, 2022 at 10:54:31AM -0600, Bjorn Helgaas wrote:
> > "sme_postprocess_startup() decrypts the bss_decrypted ection when me_mask
> > sme_is non-zero.
> 
> s/ection/section/
> 
> (In case you copy/paste this text without noticing the typo)

Thanks.

My par-agraph reformating helper does mangle words like that sometimes.
The correct sentence should be:

"sme_postprocess_startup() decrypts the bss_decrypted section when
sme_me_mask is non-zero."

/me makes a mental note to switch to the vim builtin instead.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

Re: [Patch v4 06/13] x86/hyperv: Change vTOM handling to use standard coco mechanisms

[Borislav Petkov]

On Thu, Dec 01, 2022 at 07:30:24PM -0800, Michael Kelley wrote:
> Hyper-V guests on AMD SEV-SNP hardware have the option of using the
> "virtual Top Of Memory" (vTOM) feature specified by the SEV-SNP
> architecture. With vTOM, shared vs. private memory accesses are
> controlled by splitting the guest physical address space into two
> halves.  vTOM is the dividing line where the uppermost bit of the
> physical address space is set; e.g., with 47 bits of guest physical
> address space, vTOM is 0x400000000000 (bit 46 is set).  Guest physical
> memory is accessible at two parallel physical addresses -- one below
> vTOM and one above vTOM.  Accesses below vTOM are private (encrypted)
> while accesses above vTOM are shared (decrypted). In this sense, vTOM
> is like the GPA.SHARED bit in Intel TDX.
> 
> Support for Hyper-V guests using vTOM was added to the Linux kernel in
> two patch sets[1][2]. This support treats the vTOM bit as part of
> the physical address. For accessing shared (decrypted) memory, these
> patch sets create a second kernel virtual mapping that maps to physical
> addresses above vTOM.
> 
> A better approach is to treat the vTOM bit as a protection flag, not
> as part of the physical address. This new approach is like the approach
> for the GPA.SHARED bit in Intel TDX. Rather than creating a second kernel
> virtual mapping, the existing mapping is updated using recently added
> coco mechanisms.  When memory is changed between private and shared using
> set_memory_decrypted() and set_memory_encrypted(), the PTEs for the
> existing kernel mapping are changed to add or remove the vTOM bit
> in the guest physical address, just as with TDX. The hypercalls to
> change the memory status on the host side are made using the existing
> callback mechanism. Everything just works, with a minor tweak to map
> the IO-APIC to use private accesses.
> 
> To accomplish the switch in approach, the following must be done in
> this single patch:

s/in this single patch//

> * Update Hyper-V initialization to set the cc_mask based on vTOM
>   and do other coco initialization.
> 
> * Update physical_mask so the vTOM bit is no longer treated as part
>   of the physical address
> 
> * Remove CC_VENDOR_HYPERV and merge the associated vTOM functionality
>   under CC_VENDOR_AMD. Update cc_mkenc() and cc_mkdec() to set/clear
>   the vTOM bit as a protection flag.
> 
> * Code already exists to make hypercalls to inform Hyper-V about pages
>   changing between shared and private.  Update this code to run as a
>   callback from __set_memory_enc_pgtable().
> 
> * Remove the Hyper-V special case from __set_memory_enc_dec()
> 
> * Remove the Hyper-V specific call to swiotlb_update_mem_attributes()
>   since mem_encrypt_init() will now do it.
> 
> [1] https://lore.kernel.org/all/20211025122116.264793-1-ltykernel@gmail.com/
> [2] https://lore.kernel.org/all/20211213071407.314309-1-ltykernel@gmail.com/
> 
> Signed-off-by: Michael Kelley <mikelley@microsoft.com>
> ---
>  arch/x86/coco/core.c             | 37 ++++++++++++++++++++--------
>  arch/x86/hyperv/hv_init.c        | 11 ---------
>  arch/x86/hyperv/ivm.c            | 52 +++++++++++++++++++++++++++++++---------
>  arch/x86/include/asm/coco.h      |  1 -
>  arch/x86/include/asm/mshyperv.h  |  8 ++-----
>  arch/x86/include/asm/msr-index.h |  1 +
>  arch/x86/kernel/cpu/mshyperv.c   | 15 ++++++------
>  arch/x86/mm/pat/set_memory.c     |  3 ---
>  8 files changed, 78 insertions(+), 50 deletions(-)
> 
> diff --git a/arch/x86/coco/core.c b/arch/x86/coco/core.c
> index 49b44f8..c361c52 100644
> --- a/arch/x86/coco/core.c
> +++ b/arch/x86/coco/core.c
> @@ -44,6 +44,24 @@ static bool intel_cc_platform_has(enum cc_attr attr)
>  static bool amd_cc_platform_has(enum cc_attr attr)
>  {
>  #ifdef CONFIG_AMD_MEM_ENCRYPT
> +
> +	/*
> +	 * Handle the SEV-SNP vTOM case where sme_me_mask must be zero,
> +	 * and the other levels of SME/SEV functionality, including C-bit
> +	 * based SEV-SNP, must not be enabled.
> +	 */
> +	if (sev_status & MSR_AMD64_SNP_VTOM_ENABLED) {

		return amd_cc_platform_vtom();

or so and then stick that switch in there.

This way it looks kinda grafted in front and with a function call with a telling
name it says it is a special case...

> +		switch (attr) {
> +		case CC_ATTR_GUEST_MEM_ENCRYPT:
> +		case CC_ATTR_MEM_ENCRYPT:
> +		case CC_ATTR_ACCESS_IOAPIC_ENCRYPTED:
> +			return true;
> +		default:
> +			return false;
> +		}
> +	}

The rest looks kinda nice, I gotta say. I can't complain. :)

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

RE: [Patch v4 06/13] x86/hyperv: Change vTOM handling to use standard coco mechanisms

[Michael Kelley (LINUX)]

From: Borislav Petkov <bp@alien8.de> Sent: Monday, January 9, 2023 8:39 AM
> 
[snip]

> > diff --git a/arch/x86/coco/core.c b/arch/x86/coco/core.c
> > index 49b44f8..c361c52 100644
> > --- a/arch/x86/coco/core.c
> > +++ b/arch/x86/coco/core.c
> > @@ -44,6 +44,24 @@ static bool intel_cc_platform_has(enum cc_attr attr)
> >  static bool amd_cc_platform_has(enum cc_attr attr)
> >  {
> >  #ifdef CONFIG_AMD_MEM_ENCRYPT
> > +
> > +	/*
> > +	 * Handle the SEV-SNP vTOM case where sme_me_mask must be zero,
> > +	 * and the other levels of SME/SEV functionality, including C-bit
> > +	 * based SEV-SNP, must not be enabled.
> > +	 */
> > +	if (sev_status & MSR_AMD64_SNP_VTOM_ENABLED) {
> 
> 		return amd_cc_platform_vtom();
> 
> or so and then stick that switch in there.
> 
> This way it looks kinda grafted in front and with a function call with a telling
> name it says it is a special case...
> 
> > +		switch (attr) {
> > +		case CC_ATTR_GUEST_MEM_ENCRYPT:
> > +		case CC_ATTR_MEM_ENCRYPT:
> > +		case CC_ATTR_ACCESS_IOAPIC_ENCRYPTED:
> > +			return true;
> > +		default:
> > +			return false;
> > +		}
> > +	}
> 
> The rest looks kinda nice, I gotta say. I can't complain. :)
> 

OK.  I have no objection to putting that code in a separate "helper"
function.  The only slight messiness is that the helper function must
be separately wrapped in #ifdef CONFIG_AMD_MEM_ENCRYPT, or
marked __maybe_unused.

Michael

Re: [Patch v4 07/13] swiotlb: Remove bounce buffer remapping for Hyper-V

[Borislav Petkov]

On Thu, Dec 01, 2022 at 07:30:25PM -0800, Michael Kelley wrote:
> With changes to how Hyper-V guest VMs flip memory between private
> (encrypted) and shared (decrypted), creating a second kernel virtual
> mapping for shared memory is no longer necessary. Everything needed
> for the transition to shared is handled by set_memory_decrypted().
> 
> As such, remove swiotlb_unencrypted_base and the associated
> code.
> 
> Signed-off-by: Michael Kelley <mikelley@microsoft.com>
> Acked-by: Christoph Hellwig <hch@lst.de>
> ---
>  arch/x86/kernel/cpu/mshyperv.c |  7 +------
>  include/linux/swiotlb.h        |  2 --
>  kernel/dma/swiotlb.c           | 45 +-----------------------------------------
>  3 files changed, 2 insertions(+), 52 deletions(-)

Patches removing crap are always nice:

Acked-by: Borislav Petkov (AMD) <bp@alien8.de>

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

Re: [Patch v4 06/13] x86/hyperv: Change vTOM handling to use standard coco mechanisms

[Borislav Petkov]

On Mon, Jan 09, 2023 at 05:37:00PM +0000, Michael Kelley (LINUX) wrote:
> OK.  I have no objection to putting that code in a separate "helper"
> function.  The only slight messiness is that the helper function must
> be separately wrapped in #ifdef CONFIG_AMD_MEM_ENCRYPT, or
> marked __maybe_unused.

I'd vote for __maybe_unused as that doesn't mean more ifdeffery.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

Re: [Patch v4 00/13] Add PCI pass-thru support to Hyper-V Confidential VMs

[Borislav Petkov]

On Thu, Dec 01, 2022 at 07:30:18PM -0800, Michael Kelley wrote:
> This patch series adds support for PCI pass-thru devices to Hyper-V
> Confidential VMs (also called "Isolation VMs"). But in preparation, it
> first changes how private (encrypted) vs. shared (decrypted) memory is
> handled in Hyper-V SEV-SNP guest VMs. The new approach builds on the
> confidential computing (coco) mechanisms introduced in the 5.19 kernel
> for TDX support and significantly reduces the amount of Hyper-V specific
> code. Furthermore, with this new approach a proposed RFC patch set for
> generic DMA layer functionality[1] is no longer necessary.

In any case, this is starting to get ready - how do we merge this?

I apply the x86 bits and give Wei an immutable branch to add the rest of the
HyperV stuff ontop?

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

Re: [Patch v4 04/13] x86/mm: Handle decryption/re-encryption of bss_decrypted consistently

[Borislav Petkov]

On Thu, Dec 29, 2022 at 04:25:16PM +0000, Michael Kelley (LINUX) wrote:
> I'm ambivalent on the backport to stable.  One might argue that older
> kernel versions are conceptually wrong in using different conditions for
> the decryption and re-encryption.  But as you said, they aren't broken
> from a practical standpoint because sme_me_mask and
> CC_ATTR_MEM_ENCRYPT are equivalent prior to my patch set.  However,
> the email thread with Sathyanarayanan Kuppuswamy, Tom Lendacky,
> and Dexuan Cui concluded that a Fixes: tag is appropriate.

Right, just talked to Tom offlist.

A Fixes tag triggers a lot of backporting activity and if it is not really
needed, then let's leave it out.

If distros decide to pick up vTOM support, then they'll pick up the whole set
anyway.

And if we decide we really need it backported for whatever reason, we will
simply send it into stable and the same backporting activity will be triggered
then. But then we'd at least have a concrete reason for it.

Makes sense?

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

RE: [Patch v4 04/13] x86/mm: Handle decryption/re-encryption of bss_decrypted consistently

[Michael Kelley (LINUX)]

From: Borislav Petkov <bp@alien8.de> Sent: Monday, January 9, 2023 11:11 AM
> 
> On Thu, Dec 29, 2022 at 04:25:16PM +0000, Michael Kelley (LINUX) wrote:
> > I'm ambivalent on the backport to stable.  One might argue that older
> > kernel versions are conceptually wrong in using different conditions for
> > the decryption and re-encryption.  But as you said, they aren't broken
> > from a practical standpoint because sme_me_mask and
> > CC_ATTR_MEM_ENCRYPT are equivalent prior to my patch set.  However,
> > the email thread with Sathyanarayanan Kuppuswamy, Tom Lendacky,
> > and Dexuan Cui concluded that a Fixes: tag is appropriate.
> 
> Right, just talked to Tom offlist.
> 
> A Fixes tag triggers a lot of backporting activity and if it is not really
> needed, then let's leave it out.
> 
> If distros decide to pick up vTOM support, then they'll pick up the whole set
> anyway.
> 
> And if we decide we really need it backported for whatever reason, we will
> simply send it into stable and the same backporting activity will be triggered
> then. But then we'd at least have a concrete reason for it.
> 
> Makes sense?
> 

Yep, that matches my thinking.  I've avoided marking something for stable unless
it fixes something that is actually broken.

Michael

RE: [Patch v4 00/13] Add PCI pass-thru support to Hyper-V Confidential VMs

[Michael Kelley (LINUX)]

From: Borislav Petkov <bp@alien8.de> Sent: Monday, January 9, 2023 10:47 AM
> 
> On Thu, Dec 01, 2022 at 07:30:18PM -0800, Michael Kelley wrote:
> > This patch series adds support for PCI pass-thru devices to Hyper-V
> > Confidential VMs (also called "Isolation VMs"). But in preparation, it
> > first changes how private (encrypted) vs. shared (decrypted) memory is
> > handled in Hyper-V SEV-SNP guest VMs. The new approach builds on the
> > confidential computing (coco) mechanisms introduced in the 5.19 kernel
> > for TDX support and significantly reduces the amount of Hyper-V specific
> > code. Furthermore, with this new approach a proposed RFC patch set for
> > generic DMA layer functionality[1] is no longer necessary.
> 
> In any case, this is starting to get ready - how do we merge this?
> 
> I apply the x86 bits and give Wei an immutable branch to add the rest of the
> HyperV stuff ontop?
> 
> --
> Regards/Gruss,
>     Boris.
> 

I'll let Wei respond on handling the merging.

I'll spin a v5 in a few days.  Changes will be:
* Address your comments

* Use PAGE_KERNEL in the arch independent Hyper-V code instead of
   PAGE_KERNEL_NOENC.  PAGE_KERNEL_NOENC doesn't exist for ARM64, so
   it causes compile errors when building for ARM64.  Using PAGE_KERNEL means
   getting sme_me_mask when on x86, but that value will be zero for vTOM VMs.

* Fix a problem with the virtual TPM device getting mapped decrypted.  Like
   the IOAPIC, the vTPM is provided by the paravisor, and needs to be mapped
   encrypted.   My thinking is to allow hypervisor initialization code to specify
   a guest physical address range to be treated as encrypted, and add a check against
   that range in __ioremap_check_other(), similar to what is done for EFI memory.
   Thoughts?  I don't want to change the vTPM driver, and the devm_* interfaces
   it uses don't provide an option to map encrypted anyway.  But I'm open to
   other ideas.

Thanks for the review!

Michael

Re: [Patch v4 00/13] Add PCI pass-thru support to Hyper-V Confidential VMs

[Wei Liu]

On Mon, Jan 09, 2023 at 07:47:08PM +0100, Borislav Petkov wrote:
> On Thu, Dec 01, 2022 at 07:30:18PM -0800, Michael Kelley wrote:
> > This patch series adds support for PCI pass-thru devices to Hyper-V
> > Confidential VMs (also called "Isolation VMs"). But in preparation, it
> > first changes how private (encrypted) vs. shared (decrypted) memory is
> > handled in Hyper-V SEV-SNP guest VMs. The new approach builds on the
> > confidential computing (coco) mechanisms introduced in the 5.19 kernel
> > for TDX support and significantly reduces the amount of Hyper-V specific
> > code. Furthermore, with this new approach a proposed RFC patch set for
> > generic DMA layer functionality[1] is no longer necessary.
> 
> In any case, this is starting to get ready - how do we merge this?
> 
> I apply the x86 bits and give Wei an immutable branch to add the rest of the
> HyperV stuff ontop?

I can take all the patches if that's easier for you. I don't think
anyone else is depending on the x86 patches in this series.

Giving me an immutable branch works too.

Thanks,
Wei.

> 
> -- 
> Regards/Gruss,
>     Boris.
> 
> https://people.kernel.org/tglx/notes-about-netiquette

RE: [Patch v4 00/13] Add PCI pass-thru support to Hyper-V Confidential VMs

[Dexuan Cui]

> From: Wei Liu <wei.liu@kernel.org>
> Sent: Thursday, January 12, 2023 6:04 AM
> To: Borislav Petkov <bp@alien8.de>
> [...]
> On Mon, Jan 09, 2023 at 07:47:08PM +0100, Borislav Petkov wrote:
> > On Thu, Dec 01, 2022 at 07:30:18PM -0800, Michael Kelley wrote:
> > > This patch series adds support for PCI pass-thru devices to Hyper-V
> > > Confidential VMs (also called "Isolation VMs"). But in preparation, it
> > > first changes how private (encrypted) vs. shared (decrypted) memory is
> > > handled in Hyper-V SEV-SNP guest VMs. The new approach builds on the
> > > confidential computing (coco) mechanisms introduced in the 5.19 kernel
> > > for TDX support and significantly reduces the amount of Hyper-V specific
> > > code. Furthermore, with this new approach a proposed RFC patch set for
> > > generic DMA layer functionality[1] is no longer necessary.
> >
> > In any case, this is starting to get ready - how do we merge this?
> >
> > I apply the x86 bits and give Wei an immutable branch to add the rest of the
> > HyperV stuff ontop?
> 
> I can take all the patches if that's easier for you. I don't think
> anyone else is depending on the x86 patches in this series.
> 
> Giving me an immutable branch works too.
> 
> Thanks,
> Wei.
> > --
> > Regards/Gruss,
> >     Boris.

Hi Boris, Wei, any news on this?

Re: [Patch v4 00/13] Add PCI pass-thru support to Hyper-V Confidential VMs

[Borislav Petkov]

On Thu, Jan 12, 2023 at 02:03:35PM +0000, Wei Liu wrote:
> I can take all the patches if that's easier for you. I don't think
> anyone else is depending on the x86 patches in this series.

But we have a bunch of changes in tip so I'd prefer if all were in one place.

> Giving me an immutable branch works too.

Yap, lemme do that after applying.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

Re: [Patch v4 00/13] Add PCI pass-thru support to Hyper-V Confidential VMs

[Wei Liu]

On Fri, Jan 20, 2023 at 12:58:29PM +0100, Borislav Petkov wrote:
> On Thu, Jan 12, 2023 at 02:03:35PM +0000, Wei Liu wrote:
> > I can take all the patches if that's easier for you. I don't think
> > anyone else is depending on the x86 patches in this series.
> 
> But we have a bunch of changes in tip so I'd prefer if all were in one place.
> 
> > Giving me an immutable branch works too.
> 
> Yap, lemme do that after applying.
> 
Ack. Thanks!

Wei.