KVM: SEV: Use READ_ONCE() when reading entries/indices from PSC buffer

{
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "arch/x86/kvm/svm/sev.c"
                    ],
                    "versions": [
                        {
                            "version": "9b54e248d2644be71cb394eb85f31ad99e023a05",
                            "lessThan": "bd232801ef1d1fd985d2d4ca3cd1d888303ca86f",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "9b54e248d2644be71cb394eb85f31ad99e023a05",
                            "lessThan": "b1dfaa6f7a957726a6800135be3659fbe4bbf2a4",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "9b54e248d2644be71cb394eb85f31ad99e023a05",
                            "lessThan": "edbbe88f83b524434974e84808d3093199d67c24",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "9b54e248d2644be71cb394eb85f31ad99e023a05",
                            "lessThan": "c8cc238093ca6c99267032f6cfe78f59389f3157",
                            "status": "affected",
                            "versionType": "git"
                        }
                    ]
                }

{
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "affected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "arch/x86/kvm/svm/sev.c"
                    ],
                    "versions": [
                        {
                            "version": "6.11",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "6.11",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.12.93",
                            "lessThanOrEqual": "6.12.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.18.35",
                            "lessThanOrEqual": "6.18.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.0.12",
                            "lessThanOrEqual": "7.0.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.1",
                            "lessThanOrEqual": "*",
                            "status": "unaffected",
                            "versionType": "original_commit_for_fix"
                        }
                    ]
                }