| From: |
| Mark Rutland <mark.rutland-AT-arm.com> |
| To: |
| linux-arm-kernel-AT-lists.infradead.org |
| Subject: |
| [PATCH v2 0/8] KVM: arm64: FPSIMD/SVE/SME fixes |
| Date: |
| Thu, 06 Feb 2025 14:10:54 +0000 |
| Message-ID: |
| <20250206141102.954688-1-mark.rutland@arm.com> |
| Cc: |
| broonie-AT-kernel.org, catalin.marinas-AT-arm.com, eauger-AT-redhat.com, eric.auger-AT-redhat.com, fweimer-AT-redhat.com, jeremy.linton-AT-arm.com, mark.rutland-AT-arm.com, maz-AT-kernel.org, oliver.upton-AT-linux.dev, pbonzini-AT-redhat.com, stable-AT-vger.kernel.org, tabba-AT-google.com, wilco.dijkstra-AT-arm.com, will-AT-kernel.org |
| Archive-link: |
| Article |
These patches fix some issues with the way KVM manages FPSIMD/SVE/SME
state. The series supersedes my earlier attempt at fixing the host SVE
state corruption issue:
https://lore.kernel.org/linux-arm-kernel/20250121100026.3...
Patch 1 addresses the host SVE state corruption issue by always saving
and unbinding the host state when loading a vCPU, as discussed on the
earlier patch:
https://lore.kernel.org/linux-arm-kernel/Z4--YuG5SWrP_pW7...
https://lore.kernel.org/linux-arm-kernel/86plkful48.wl-ma...
Patches 2 to 4 remove code made redundant by patch 1. These probably
warrant backporting along with patch 1 as there is some historical
brokenness in the code they remove.
Patches 5 to 7 are preparatory refactoring for patch 8, and are not
intended to have any functional impact.
Patch 8 addresses some mismanagement of ZCR_EL{1,2} which can result in
the host VMM unexpectedly receiving a SIGKILL. To fix this, we eagerly
switch ZCR_EL{1,2} at guest<->host transitions, as discussed on another
series:
https://lore.kernel.org/linux-arm-kernel/Z4pAMaEYvdLpmbg2...
https://lore.kernel.org/linux-arm-kernel/86o6zzukwr.wl-ma...
https://lore.kernel.org/linux-arm-kernel/Z5Dc-WMu2azhTuMn...
The end result is that KVM loses ~100 lines of code, and becomes a bit
simpler to reason about.
I've pushed these patches to the arm64-kvm-fpsimd-fixes-20250206 tag on
my kernel.org repo:
https://git.kernel.org/pub/scm/linux/kernel/git/mark/linu...
git://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git
The (unstable) arm64/kvm/fpsimd-fixes branch in that repo contains the
fixes plus additional debug patches I've used for testing. I've given
this some basic testing on a virtual platform, booting a host and a
guest with and without constraining the guest's max SVE VL, with:
* kvm_arm.mode=vhe
* kvm_arm.mode=nvhe
* kvm_arm.mode=protected (IIUC this will default to hVHE)
Since v1 [1]:
* Address some additional compiler warnings in patch 7
* Use ZCR_EL1 alias in VHE code
* Fold in Tested-by and Reviewed-by tags
* Fix typos
[1] https://lore.kernel.org/linux-arm-kernel/20250204152100.7...
Mark.
Mark Rutland (8):
KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state
KVM: arm64: Remove host FPSIMD saving for non-protected KVM
KVM: arm64: Remove VHE host restore of CPACR_EL1.ZEN
KVM: arm64: Remove VHE host restore of CPACR_EL1.SMEN
KVM: arm64: Refactor CPTR trap deactivation
KVM: arm64: Refactor exit handlers
KVM: arm64: Mark some header functions as inline
KVM: arm64: Eagerly switch ZCR_EL{1,2}
arch/arm64/include/asm/kvm_emulate.h | 42 --------
arch/arm64/include/asm/kvm_host.h | 22 +----
arch/arm64/kernel/fpsimd.c | 25 -----
arch/arm64/kvm/arm.c | 8 --
arch/arm64/kvm/fpsimd.c | 100 ++-----------------
arch/arm64/kvm/hyp/include/hyp/switch.h | 125 +++++++++++++++++-------
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 15 ++-
arch/arm64/kvm/hyp/nvhe/switch.c | 91 ++++++++---------
arch/arm64/kvm/hyp/vhe/switch.c | 33 ++++---
9 files changed, 174 insertions(+), 287 deletions(-)
--
2.30.2
