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SUSE:SLE-15-SP5:GA
xen.8389
5ad600d4-x86-pv-introduce-x86emul_read_dr.patch
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File 5ad600d4-x86-pv-introduce-x86emul_read_dr.patch of Package xen.8389
# Commit 881f8dc4314809293efc6f66f9af49734994bf0e # Date 2018-04-17 15:12:36 +0100 # Author Andrew Cooper <andrew.cooper3@citrix.com> # Committer Andrew Cooper <andrew.cooper3@citrix.com> x86/pv: Introduce and use x86emul_read_dr() do_get_debugreg() has several bugs: * The %cr4.de condition is inverted. %dr4/5 should be accessible only when %cr4.de is disabled. * When %cr4.de is disabled, emulation should yield #UD rather than complete with zero. * Using -EINVAL for errors is a broken ABI, as it overlaps with valid values near the top of the address space. Introduce a common x86emul_read_dr() handler (as we will eventually want to add HVM support) which separates its success/failure indication from the data value, and have do_get_debugreg() call into the handler. The ABI of do_get_debugreg() remains broken, but switches from -EINVAL to -ENODEV for compatibility with the changes in the following patch. Take the opportunity to add a missing local variable block to x86_emulate.c Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Acked-by: Jan Beulich <jbeulich@suse.com> --- a/xen/arch/x86/pv/emul-priv-op.c +++ b/xen/arch/x86/pv/emul-priv-op.c @@ -813,19 +813,6 @@ static int write_cr(unsigned int reg, un return X86EMUL_UNHANDLEABLE; } -static int read_dr(unsigned int reg, unsigned long *val, - struct x86_emulate_ctxt *ctxt) -{ - unsigned long res = do_get_debugreg(reg); - - if ( IS_ERR_VALUE(res) ) - return X86EMUL_UNHANDLEABLE; - - *val = res; - - return X86EMUL_OKAY; -} - static int write_dr(unsigned int reg, unsigned long val, struct x86_emulate_ctxt *ctxt) { @@ -1326,7 +1313,7 @@ static const struct x86_emulate_ops priv .read_segment = read_segment, .read_cr = read_cr, .write_cr = write_cr, - .read_dr = read_dr, + .read_dr = x86emul_read_dr, .write_dr = write_dr, .read_msr = read_msr, .write_msr = write_msr, --- a/xen/arch/x86/pv/misc-hypercalls.c +++ b/xen/arch/x86/pv/misc-hypercalls.c @@ -30,22 +30,10 @@ long do_set_debugreg(int reg, unsigned l unsigned long do_get_debugreg(int reg) { - struct vcpu *curr = current; + unsigned long val; + int res = x86emul_read_dr(reg, &val, NULL); - switch ( reg ) - { - case 0 ... 3: - case 6: - return curr->arch.debugreg[reg]; - case 7: - return (curr->arch.debugreg[7] | - curr->arch.debugreg[5]); - case 4 ... 5: - return ((curr->arch.pv_vcpu.ctrlreg[4] & X86_CR4_DE) ? - curr->arch.debugreg[reg + 2] : 0); - } - - return -EINVAL; + return res == X86EMUL_OKAY ? val : -ENODEV; } long do_fpu_taskswitch(int set) --- a/xen/arch/x86/x86_emulate.c +++ b/xen/arch/x86/x86_emulate.c @@ -41,3 +41,52 @@ }) #include "x86_emulate/x86_emulate.c" + +/* Called with NULL ctxt in hypercall context. */ +int x86emul_read_dr(unsigned int reg, unsigned long *val, + struct x86_emulate_ctxt *ctxt) +{ + struct vcpu *curr = current; + + /* HVM support requires a bit more plumbing before it will work. */ + ASSERT(is_pv_vcpu(curr)); + + switch ( reg ) + { + case 0 ... 3: + case 6: + *val = curr->arch.debugreg[reg]; + break; + + case 7: + *val = (curr->arch.debugreg[7] | + curr->arch.debugreg[5]); + break; + + case 4 ... 5: + if ( !(curr->arch.pv_vcpu.ctrlreg[4] & X86_CR4_DE) ) + { + *val = curr->arch.debugreg[reg + 2]; + break; + } + + /* Fallthrough */ + default: + if ( ctxt ) + x86_emul_hw_exception(TRAP_invalid_op, X86_EVENT_NO_EC, ctxt); + + return X86EMUL_EXCEPTION; + } + + return X86EMUL_OKAY; +} + +/* + * Local variables: + * mode: C + * c-file-style: "BSD" + * c-basic-offset: 4 + * tab-width: 4 + * indent-tabs-mode: nil + * End: + */ --- a/xen/arch/x86/x86_emulate/x86_emulate.h +++ b/xen/arch/x86/x86_emulate/x86_emulate.h @@ -662,6 +662,9 @@ static inline void x86_emulate_free_stat void x86_emulate_free_state(struct x86_emulate_state *state); #endif +int x86emul_read_dr(unsigned int reg, unsigned long *val, + struct x86_emulate_ctxt *ctxt); + #endif static inline void x86_emul_hw_exception(
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