This patch series fixes up and tries to remove some confusion around the SEV reduced-phys-bits parameter. Based on the "AMD64 Architecture Programmer's Manual Volume 2: System Programming", section "15.34.6 Page Table Support" [1], a guest should only ever see a maximum of 1 bit of physical address space reduction. - Update the documentation, to change the default value from 5 to 1. - Update the validation of the parameter to ensure the parameter value is within the range of the CPUID field that it is reported in. To allow for backwards compatibility, especially to support the previously documented value of 5, allow the full range of values from 1 to 63 (0 was never allowed). - Update the setting of CPUID 0x8000001F_EBX to limit the values to the field width that they are setting as an additional safeguard. [1] https://www.amd.com/system/files/TechDocs/24593.pdf Tom Lendacky (4): qapi, i386/sev: Change the reduced-phys-bits value from 5 to 1 qemu-options.hx: Update the reduced-phys-bits documentation i386/sev: Update checks and information related to reduced-phys-bits i386/cpu: Update how the EBX register of CPUID 0x8000001F is set qapi/misc-target.json | 2 +- qemu-options.hx | 4 ++-- target/i386/cpu.c | 4 ++-- target/i386/sev.c | 17 ++++++++++++++--- 4 files changed, 19 insertions(+), 8 deletions(-) -- 2.37.3
