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Introduce support for movable memory regions in the Hyper-V root partition
driver to improve memory management flexibility and enable advanced use
cases such as dynamic memory remapping.
Mirror the address space between the Linux root partition and guest VMs
using HMM. The root partition owns the memory, while guest VMs act as
devices with page tables managed via hypercalls. MSHV handles VP intercepts
by invoking hmm_range_fault() and updating SLAT entries. When memory is
reclaimed, HMM invalidates the relevant regions, prompting MSHV to clear
SLAT entries; guest VMs will fault again on access.
Integrate mmu_interval_notifier for movable regions, implement handlers for
HMM faults and memory invalidation, and update memory region mapping logic
to support movable regions.
While MMU notifiers are commonly used in virtualization drivers, this
implementation leverages HMM (Heterogeneous Memory Management) for its
specialized functionality. HMM provides a framework for mirroring,
invalidation, and fault handling, reducing boilerplate and improving
maintainability compared to generic MMU notifiers.
Signed-off-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Reviewed-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
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Introduce kref-based reference counting and spinlock protection for
memory regions in Hyper-V partition management. This change improves
memory region lifecycle management and ensures thread-safe access to the
region list.
Previously, the regions list was protected by the partition mutex.
However, this approach is too heavy for frequent fault and invalidation
operations. Finer grained locking is now used to improve efficiency and
concurrency.
This is a precursor to supporting movable memory regions. Fault and
invalidation handling for movable regions will require safe traversal of
the region list and holding a region reference while performing
invalidation or fault operations.
Signed-off-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
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The previous code assumed that if a region's first page was huge, the
entire region consisted of huge pages and stored this in a large_pages
flag. This premise is incorrect not only for movable regions (where
pages can be split and merged on invalidate callbacks or page faults),
but even for pinned regions: THPs can be split and merged during
allocation, so a large, pinned region may contain a mix of huge and
regular pages.
This change removes the large_pages flag and replaces region-wide
assumptions with per-chunk inspection of the actual page size when
mapping, unmapping, sharing, and unsharing. This makes huge page
handling correct for mixed-page regions and avoids relying on stale
metadata that can easily become invalid as memory is remapped.
Signed-off-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Reviewed-by: Anirudh Rayabharam (Microsoft) <anirudh@anirudhrb.com>
Reviewed-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
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Refactor memory region management functions from mshv_root_main.c into
mshv_regions.c for better modularity and code organization.
Adjust function calls and headers to use the new implementation. Improve
maintainability and separation of concerns in the mshv_root module.
Signed-off-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Reviewed-by: Anirudh Rayabharam (Microsoft) <anirudh@anirudhrb.com>
Reviewed-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
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Introduce HVCALL_MAP_STATS_PAGE2 which provides a map location (GPFN)
to map the stats to. This hypercall is required for L1VH partitions,
depending on the hypervisor version. This uses the same check as the
state page map location; mshv_use_overlay_gpfn().
Add mshv_map_vp_state_page() helpers to use this new hypercall or the
old one depending on availability.
For unmapping, the original HVCALL_UNMAP_STATS_PAGE works for both
cases.
Signed-off-by: Jinank Jain <jinankjain@linux.microsoft.com>
Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Easwar Hariharan <easwar.hariharan@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
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Introduce mshv_use_overlay_gpfn() to check if a page needs to be
allocated and passed to the hypervisor to map VP state pages. This is
only needed on L1VH, and only on some (newer) versions of the
hypervisor, hence the need to check vmm_capabilities.
Introduce functions hv_map/unmap_vp_state_page() to handle the
allocation and freeing.
Signed-off-by: Jinank Jain <jinankjain@linux.microsoft.com>
Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Praveen K Paladugu <prapal@linux.microsoft.com>
Reviewed-by: Easwar Hariharan <easwar.hariharan@linux.microsoft.com>
Reviewed-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Reviewed-by: Anirudh Rayabharam <anirudh@anirudhrb.com>
Reviewed-by: Tianyu Lan <tiala@microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
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Some hypervisor APIs are gated by feature bits in the
"vmm capabilities" partition property. Store the capabilities on
mshv_root module init, using HVCALL_GET_PARTITION_PROPERTY_EX.
This is not supported on all hypervisors. In that case, just set the
capabilities to 0 and proceed as normal.
Signed-off-by: Purna Pavan Chandra Aekkaladevi <paekkaladevi@linux.microsoft.com>
Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Praveen K Paladugu <prapal@linux.microsoft.com>
Reviewed-by: Easwar Hariharan <easwar.hariharan@linux.microsoft.com>
Reviewed-by: Tianyu Lan <tiala@microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
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This hypercall can be used to fetch extended properties of a
partition. Extended properties are properties with values larger than
a u64. Some of these also need additional input arguments.
Add helper function for using the hypercall in the mshv_root driver.
Signed-off-by: Purna Pavan Chandra Aekkaladevi <paekkaladevi@linux.microsoft.com>
Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Anirudh Rayabharam <anirudh@anirudhrb.com>
Reviewed-by: Praveen K Paladugu <prapal@linux.microsoft.com>
Reviewed-by: Easwar Hariharan <easwar.hariharan@linux.microsoft.com>
Reviewed-by: Tianyu Lan <tiala@microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
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Confidential VMBus requires interacting with two SynICs -- one
provided by the host hypervisor, and one provided by the paravisor.
Each SynIC requires its own message and event pages.
Rename the existing host-accessible SynIC message and event pages
with the "hyp_" prefix to clearly distinguish them from the paravisor
ones. The field name is also changed in mshv_root.* for consistency.
No functional changes.
Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
Reviewed-by: Tianyu Lan <tiala@microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
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Provide a set of IOCTLs for creating and managing child partitions when
running as root partition on Hyper-V. The new driver is enabled via
CONFIG_MSHV_ROOT.
A brief overview of the interface:
MSHV_CREATE_PARTITION is the entry point, returning a file descriptor
representing a child partition. IOCTLs on this fd can be used to map
memory, create VPs, etc.
Creating a VP returns another file descriptor representing that VP which
in turn has another set of corresponding IOCTLs for running the VP,
getting/setting state, etc.
MSHV_ROOT_HVCALL is a generic "passthrough" hypercall IOCTL which can be
used for a number of partition or VP hypercalls. This is for hypercalls
that do not affect any state in the kernel driver, such as getting and
setting VP registers and partition properties, translating addresses,
etc. It is "passthrough" because the binary input and output for the
hypercall is only interpreted by the VMM - the kernel driver does
nothing but insert the VP and partition id where necessary (which are
always in the same place), and execute the hypercall.
Co-developed-by: Anirudh Rayabharam <anrayabh@linux.microsoft.com>
Signed-off-by: Anirudh Rayabharam <anrayabh@linux.microsoft.com>
Co-developed-by: Jinank Jain <jinankjain@microsoft.com>
Signed-off-by: Jinank Jain <jinankjain@microsoft.com>
Co-developed-by: Mukesh Rathor <mrathor@linux.microsoft.com>
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
Co-developed-by: Muminul Islam <muislam@microsoft.com>
Signed-off-by: Muminul Islam <muislam@microsoft.com>
Co-developed-by: Praveen K Paladugu <prapal@linux.microsoft.com>
Signed-off-by: Praveen K Paladugu <prapal@linux.microsoft.com>
Co-developed-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Signed-off-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Co-developed-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Roman Kisel <romank@linux.microsoft.com>
Link: https://lore.kernel.org/r/1741980536-3865-11-git-send-email-nunodasneves@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <1741980536-3865-11-git-send-email-nunodasneves@linux.microsoft.com>
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