OpenCloudOS-Kernel/include/uapi
Mohammed Gamal 3edd68399d KVM: x86: Add a capability for GUEST_MAXPHYADDR < HOST_MAXPHYADDR support
This patch adds a new capability KVM_CAP_SMALLER_MAXPHYADDR which
allows userspace to query if the underlying architecture would
support GUEST_MAXPHYADDR < HOST_MAXPHYADDR and hence act accordingly
(e.g. qemu can decide if it should warn for -cpu ..,phys-bits=X)

The complications in this patch are due to unexpected (but documented)
behaviour we see with NPF vmexit handling in AMD processor.  If
SVM is modified to add guest physical address checks in the NPF
and guest #PF paths, we see the followning error multiple times in
the 'access' test in kvm-unit-tests:

            test pte.p pte.36 pde.p: FAIL: pte 2000021 expected 2000001
            Dump mapping: address: 0x123400000000
            ------L4: 24c3027
            ------L3: 24c4027
            ------L2: 24c5021
            ------L1: 1002000021

This is because the PTE's accessed bit is set by the CPU hardware before
the NPF vmexit. This is handled completely by hardware and cannot be fixed
in software.

Therefore, availability of the new capability depends on a boolean variable
allow_smaller_maxphyaddr which is set individually by VMX and SVM init
routines. On VMX it's always set to true, on SVM it's only set to true
when NPT is not enabled.

CC: Tom Lendacky <thomas.lendacky@amd.com>
CC: Babu Moger <babu.moger@amd.com>
Signed-off-by: Mohammed Gamal <mgamal@redhat.com>
Message-Id: <20200710154811.418214-10-mgamal@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-07-10 17:01:53 -04:00
..
asm-generic vfs: add faccessat2 syscall 2020-05-14 16:44:25 +02:00
drm drm msm next for 5.8-rc1 2020-06-08 11:33:38 -07:00
linux KVM: x86: Add a capability for GUEST_MAXPHYADDR < HOST_MAXPHYADDR support 2020-07-10 17:01:53 -04:00
misc uapi: habanalabs: add gaudi defines 2020-05-19 14:48:41 +03:00
mtd mtd: Add support for emulated SLC mode on MLC NANDs 2020-05-11 09:51:41 +02:00
rdma RDMA 5.8 merge window pull request 2020-06-05 14:05:57 -07:00
scsi uapi: revert flexible-array conversions 2020-05-04 11:30:15 -05:00
sound ASoC: Intel: Skylake: Automatic DMIC format configuration according to information from NHLT 2020-04-27 16:02:26 +01:00
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