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| author | Lai Jiangshan <jiangshan.ljs@antgroup.com> | 2022-03-11 10:03:44 +0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2022-04-02 12:34:43 +0300 |
| commit | 4f4aa80e3b882cbbafdf95ebc018c72b10879dbb (patch) | |
| tree | 776d39bacece84f6fca92040b035fb65af663047 /arch/x86/include | |
| parent | 8873c1434fac436f68ac2221676bb148e8fdffa2 (diff) | |
| download | linux-4f4aa80e3b882cbbafdf95ebc018c72b10879dbb.tar.xz | |
KVM: X86: Handle implicit supervisor access with SMAP
There are two kinds of implicit supervisor access
implicit supervisor access when CPL = 3
implicit supervisor access when CPL < 3
Current permission_fault() handles only the first kind for SMAP.
But if the access is implicit when SMAP is on, data may not be read
nor write from any user-mode address regardless the current CPL.
So the second kind should be also supported.
The first kind can be detect via CPL and access mode: if it is
supervisor access and CPL = 3, it must be implicit supervisor access.
But it is not possible to detect the second kind without extra
information, so this patch adds an artificial PFERR_EXPLICIT_ACCESS
into @access. This extra information also works for the first kind, so
the logic is changed to use this information for both cases.
The value of PFERR_EXPLICIT_ACCESS is deliberately chosen to be bit 48
which is in the most significant 16 bits of u64 and less likely to be
forced to change due to future hardware uses it.
This patch removes the call to ->get_cpl() for access mode is determined
by @access. Not only does it reduce a function call, but also remove
confusions when the permission is checked for nested TDP. The nested
TDP shouldn't have SMAP checking nor even the L2's CPL have any bearing
on it. The original code works just because it is always user walk for
NPT and SMAP fault is not set for EPT in update_permission_bitmask.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Message-Id: <20220311070346.45023-5-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/include')
| -rw-r--r-- | arch/x86/include/asm/kvm_host.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 71cfc9fdf946..a2224037d232 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -249,6 +249,7 @@ enum x86_intercept_stage; #define PFERR_SGX_BIT 15 #define PFERR_GUEST_FINAL_BIT 32 #define PFERR_GUEST_PAGE_BIT 33 +#define PFERR_IMPLICIT_ACCESS_BIT 48 #define PFERR_PRESENT_MASK (1U << PFERR_PRESENT_BIT) #define PFERR_WRITE_MASK (1U << PFERR_WRITE_BIT) @@ -259,6 +260,7 @@ enum x86_intercept_stage; #define PFERR_SGX_MASK (1U << PFERR_SGX_BIT) #define PFERR_GUEST_FINAL_MASK (1ULL << PFERR_GUEST_FINAL_BIT) #define PFERR_GUEST_PAGE_MASK (1ULL << PFERR_GUEST_PAGE_BIT) +#define PFERR_IMPLICIT_ACCESS (1ULL << PFERR_IMPLICIT_ACCESS_BIT) #define PFERR_NESTED_GUEST_PAGE (PFERR_GUEST_PAGE_MASK | \ PFERR_WRITE_MASK | \ |