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2021-10-08Remove ring0 floating point save/load functions on amd64.Jamie Liu
ring0.Save/LoadFloatingPoint() are only usable if the caller can ensure that Go will not clobber floating point registers before/after calling them respectively. Due to regabig in Go 1.17, this is no longer the case; regabig (among other things) maintains a zeroed XMM15 during ABIInternal execution, including by zeroing it after ABI0-to-ABIInternal transitions. In ring0.sysenter/exception, this happens in ring0.kernelSyscall/kernelException.abi0 respectively; in ring0.CPU.SwitchToUser, this happens after returning from ring0.sysret/iret.abi0. Delete these functions and do floating point save/load in assembly. While arm64 doesn't appear to be immediately affected (so this CL permits us to resume usage of Go 1.17), its use of Save/LoadFloatingPoint() still seems to be incorrect for the same fundamental reason (Go code can't sanely assume what registers the Go compiler will or won't use) and should be fixed eventually. PiperOrigin-RevId: 401895658
2021-09-22kvm: trap mmap syscalls to map new regions to the guestAndrei Vagin
We install seccomp rules so that the SIGSYS signal is generated for each mmap system call. Then our signal handler executes the real mmap syscall and if a new regions is created, it maps it to the guest. Signed-off-by: Andrei Vagin <avagin@google.com>
2021-07-22kvm: set CR0.NE = 1Andrei Vagin
CR0.NE enables internal x87 floating point error reporting when set, else enables PC style x87 error detection. On AMD, the #MF exception isn't generated if CR0.NE isn't set. PiperOrigin-RevId: 386340269
2021-07-20Add go:build directives as required by Go 1.17's gofmt.Jamie Liu
PiperOrigin-RevId: 385894869
2021-07-20ring0: Initialize sentryXCR0 from Kernel.init()Andrei Vagin
Fixes #6300 PiperOrigin-RevId: 385840917
2021-07-12Go 1.17 support for the KVM platformMichael Pratt
Go 1.17 adds a new register-based calling convention. While transparent for most applications, the KVM platform needs special work in a few cases. First of all, we need the actual address of some assembly functions, rather than the address of a wrapper. See http://gvisor.dev/pr/5832 for complete discussion of this. More relevant to this CL is that ABI0-to-ABIInternal wrappers (i.e., calls from assembly to Go) access the G via FS_BASE. The KVM quite fast-and-loose about the Go environment, often calling into (nosplit) Go functions with uninitialized FS_BASE. That will no longer work in Go 1.17, so this CL changes the platform to consistently restore FS_BASE before calling into Go code. This CL does not affect arm64 code. Go 1.17 does not support the register-based calling convention for arm64 (it will come in 1.18), but arm64 also does not use a non-standard register like FS_BASE for TLS, so it may not require any changes. PiperOrigin-RevId: 384234305
2021-06-11Rework the workaround of the XCR0 issueAndrei Vagin
XCR0 has to be synchronized with the host. We can call xsave from the host context and then call xrstor from the guest context and vise versa. This means we need to support the same set of FPU features in both contexts. PiperOrigin-RevId: 378988281
2021-04-30kvm: prefault a root table page before switching into a user address spaceAndrei Vagin
The root table physical page has to be mapped to not fault in iret or sysret after switching into a user address space. sysret and iret are in the upper half that is global and so page tables of lower levels are already mapped. Fixes #5742 PiperOrigin-RevId: 371458644
2021-04-21Merge pull request #5749 from zhlhahaha:2126gVisor bot
PiperOrigin-RevId: 369686298
2021-04-09Merge pull request #5767 from avagin:mxcsrgVisor bot
PiperOrigin-RevId: 367730917
2021-04-08Merge pull request #5736 from lubinszARM:pr_bblu_tlb_asidgVisor bot
PiperOrigin-RevId: 367523491
2021-04-01platform/kvm/x86: restore mxcsr when switching from guest to sentryAndrei Vagin
Goruntime sets mxcsr once and never changes it. Reported-by: syzbot+ec55cea6e57ec083b7a6@syzkaller.appspotmail.com Fixes: #5754
2021-03-30apply hostarch on pagetables_arm64_test.goHoward Zhang
Signed-off-by: Howard Zhang <howard.zhang@arm.com>
2021-03-29[syserror] Split usermem packageZach Koopmans
Split usermem package to help remove syserror dependency in go_marshal. New hostarch package contains code not dependent on syserror. PiperOrigin-RevId: 365651233
2021-03-26arm64 ring0: don't use inner-sharable to invalidate tlbRobin Luk
It is enough to invalidate the tlb of local vcpu in switch(). TLBI with inner-sharable will invalidate the tlb in other vcpu. Arm64 hardware supports at least 256 pcid, so I think it's ok to set the length of pcid pool to 128. Signed-off-by: Robin Luk <lubin.lu@antgroup.com>
2021-03-25Fix nogo test errorHoward Zhang
Signed-off-by: Howard Zhang <howard.zhang@arm.com>
2021-03-23Move the code that manages floating-point state to a separate packageAndrei Vagin
This change is inspired by Adin's cl/355256448. PiperOrigin-RevId: 364695931
2021-02-03arm64 kvm:implement basic lazy save and restore for FPSIMD registersRobin Luk
Implement basic lazy save and restore for FPSIMD registers, which only restore FPSIMD state on el0_fpsimd_acc and save FPSIMD state in switch(). Signed-off-by: Robin Luk <lubin.lu@antgroup.com>
2021-02-03arm64: clean codeRobin Luk
In order to improve the performance and stability, I reorg 2 modules slightly. arch: no red zone on Arm64. ring0: use stp instead of movd, and set RSV_REG_APP=R19. Signed-off-by: Robin Luk <lubin.lu@antgroup.com>
2021-02-02Move ring0 package.Adin Scannell
This allows the package to serve as a general purpose ring0 support package, as opposed to being bound to specific sentry platforms. Updates #5039 PiperOrigin-RevId: 355220044
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